Seeking “Official” delineation of North American mountain ranges?

Seeking “Official” delineation of North American mountain ranges?

I need to subset mosaics of remotely sourced data to the extents of several prominent North American mountain ranges, starting with the Sierra Nevada. After searching for the boundaries of the range it has become clear to me that this isn't quite as straightforward as I thought: wikipedia, peakbagger, the California DFG, the Sierra Nevada Conservancy and my desktop copy of google earth all show clearly different boundaries for the range. Clearly, the border a mountain range is less black and white than, say, an administrative boundary.

Are there "official" (by which I mean either authoratative or generally agreed-upon) definitions of the extents of North American mountain ranges, and if so, where can they be found?

Obviously it would be nice if it existed as a shapefile, but I can digitize it myself if it's just a list of bounding points.

To clarify, I don't particularly care if the boundaries are somewhat arbitrary/inaccurate from a strict geological perspective, as long as they come from an authoritative/trusted source. I'm not studying geological processes- I just need a reasonable citation.

UNEP-WCMC came up with a definition using altitude and slope and a few other criteria that resulted in 7 classes all defined as mountainous regions. The info below is from the 2002 version.


Definition of mountainous regions:


UNEP-WCMC, 2002. Mountain Watch: Environmental Change and Sustainable Development in Mountains. UNEP-WCMC. Cambridge, UK.

Updated links (August 22, 2019): The linked data on seems to be be dead. This page has links to two similar datasets from UNEP-WCMC. Follow these links to download the datasets directly from UNEP-WCMC (you will need to fill out a short form to gain access):

While it doesn't appear as authoritative as @Ian's reference, I found that the Natural Earth label areas shapefile contains very rough delineations, which were sufficient for my purposes.

Seeking &ldquoOfficial&rdquo delineation of North American mountain ranges? - Geographic Information Systems

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Download Maps and GIS Data Sets

Shapefiles of ecoregions for the contiguous United States are available here through the U.S. Geological Survey.

In addition, the USDA Forest Service and the National Atlas of the United States® collaborated to create, and deliver for download, the following GIS data sets:


A map of the ecoregions of the United States is available for download as a .jpeg image (2.1MB compressed).

Contact Robert Bailey to receive a copy of the following posters:

Ecoregion-Based Design for Sustainability (2002), 22" x 34", Color, Rolled or Folded

Ecoregions (1998), 22" x 34", Color, Rolled or Folded

Ecosystem Geography (1996), 22" x 34", Color, Rolled or Folded



  • Bailey, Robert G. 2014. Ecoregions: The Ecosystem Geography of the Oceans and the Continents. 2nd edition. Springer-Verlag. New York, New York. 192 pp., 107 illus., 10 tables. ISBN 0-387-98305-8.

The first edition of this book (1998) classified and characterized the regional-scale ecosystem units (ecoregions) of the Earth as shown on a map that Bailey developed with the encouragement of several international organizations. Bailey is one of the pioneers that conceived and developed the ecoregion concept in addition to the descriptive account, his primary goal was to suggest explanations that act to produce the global pattern of ecoregion distribution, and to consider some of the implications for land use. He includes ocean types, since understanding land regions depends on understanding ocean systems. This second edition is a completely updated and expanded version. New sections address how ecoregions change under the relentless influence of humans and climate change, and include discussions of the use of eco-regional patterns to transfer research results and select sites for detecting climate change effects on ecosystem distribution.

Bailey, Robert G. 2009. Ecosystem Geography: From Ecoregions to Sites. 2nd edition. Springer-Verlag. New York, New York, 252 pp., 113 illus. ISBN: 978-4419-0391-4.

The first edition of this book (1996) explores the patterns of ecosystem distribution at multiple scales. It describes these patterns in terms of the mechanisms that cause them, and goes on to examine the connections between these patterns, conservation, and management. This second edition builds on the strengths of its predecessor, incorporating new information and clarifying concepts. New sections address how ecoregion boundaries were determined, discuss ecoregion redistribution under climate change, put more emphasis on ecosystem processes (such as fire regimes), and describe human modification to ecosystems, such as through the introduction of invasive species.

  • Bailey, Robert G. 2002. Ecoregion-Based Design for Sustainability. Springer-Verlag. New York, New York. 240 pp., 100 illus. ISBN: 0-387-95430-9.

This richly illustrated volume completes Robert G. Bailey's celebrated study of ecoregions, begun in the landmark Ecosystem Geography (1996) and further articulated in Ecoregions (1998). In this third installment, the author expands his system for defining large-scale ecological zones to encompass principles of land management, regional planning, and design. In an engaging, nontechnical discussion, he shows how larger patterns and processes that characterize a region — its climate, topography, soils, vegetation, fauna, and human culture — provide essential keys to the sustainability of ecosystems.

Journal Articles

Designers of the structures at Colorado's Mesa Verde National Park diverged from the National Park Service's architectural tradition at the time. The historical precedent was to borrow attractive yet incongruous design themes from the Old World with little regard for the natural setting. Instead, principal designers Jesse and Aileen Nusbaum became the first to incorporate surrounding ecological themes into the design of a National Park structure.

This article summarizes the rationale used in identifying ecoregion boundaries on maps of the United States, North America, and the world's continents, published from 1976 to 1998. The geographic reasoning behind boundaries involves 20 principles, which are presented to stimulate discussion and further understanding.

  • Omernik, James M. Bailey, Robert G. 1997. Distinguishing between watersheds and ecoregions. Journal of the American Water Resources Association 33(5):935-949.

Many state and federal agencies have begun using watershed or ecoregion frameworks. Misunderstanding of each of the frameworks has resulted in inconsistency in their use and ultimate effectiveness. The focus of this paper is on the clarification of both frameworks. The issue is not whether to use watersheds or ecoregions frameworks, but how to correctly use the frameworks together.

World-wide monitoring of agricultural and other natural-resource ecosystems is needed in assessing the effects of possible climate changes and/or air pollution on our global resource-base. Monitoring of all sites is neither possible nor desirable for large areas, and so a means of choice has to be devised and implemented.

As part of the planning process, maps of natural factors are often superimposed in order to identify areas which are suitable or unsuitable for a particular type of resource management. Current interest in applying computer-assisted mapping technology is drawing attention to geographic information systems. The resultant maps, however, may be so inaccurate that they could lead to imperfect or false conclusions. Recommendations are made on how to proceed in light of these problems.

Natural resource management occurs at varying levels from national to site-specific, creating the need for a hierarchical system of ecosystem units, defined according to criteria that make them relevant to the kinds of questions being asked at different levels of management decisions. A set of criteria for sub-dividing a landscape into ecosystems of different size is presented, based on factors important in controlling ecosystem size at varying scales in a hierarchy.

Ecosystems come in many scales or relative sizes. The relationships between smaller and larger scales must be examined in order to predict the effects of management prescriptions on resource outputs. Environmental factors important in controlling ecosystem size change in nature with the scale of observation. Environmental factors that are thought to be useful in recognizing and mapping ecosystems at various scales are reviewed.

As a means of developing reliable estimates of ecosystem productivity, landscapes need to be stratified into homogeneous geographic regions. Such ecosystem regions are hypothesized to be productively different in important ways. One measure of the difference is hydrologic productivity. Data from 53 hydrologic bench-mark stations within major ecosystem regions were subjected to discriminant analysis. The ecosystem regions tested in this study exhibit a high degree of ability to circumscribe stations with similar hydrologic productivity.

As a means of developing reliable estimates of ecosystem productivity, ecosystem classification needs to be placed within a geographical framework of regions or zones. This paper explains the basis for the regions delineated on the 1976 map Ecoregions of the United States. Four ecological levels are discussed — domain, division, province, and section — based on climatic and vegetational criteria. Statistical tests are needed to verify and refine map units.

Government Publications

  • Bailey, Robert G. 2010. Fire regimes and ecoregions. Pp 7-18 in Elliot, William J. Miller, Ina Sue Audin, Lisa (eds.). Cumulative watershed effects of fuel management in the western United States. General Technical Report RMRS-GTR-231. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

The majority of American forest and grassland ecosystems are adapted to fire of varying frequencies and magnitudes. Fire-excluded systems are prone to changes in composition and density, and are susceptible to catastrophic fire and invasion by non-native species. Planning for fire and land management policies must incorporate an improved understanding of fire regimes. This paper discusses fire regimes of different ecosystems at the scale of ecoregion, and goes on to explore how understanding fire regimes can abate the threat of fire exclusion and restore fire-adapted ecosystems.

  • Bailey, Robert G. 2009. Research applications of ecosystem patterns. Pp 83-90 in McRoberts, Ronald E. Reams, Gregory A. Van Deusen, Paul C. McWilliams, William H. (eds.). Proceedings of the eighth annual forest inventory and analysis symposium 2006 October 16-19 Monterey, CA. General Technical Report WO-79. Washington, DC: U.S. Department of Agriculture, Forest Service.

This article discusses the origins of natural ecosystem patterns from global to local scales. It describes how understanding these patterns can help scientists and managers in two ways. First, the local systems are shown within the context of larger systems. This perspective can be applied in assessing the connections between action at one scale and effect at another, the spatial transferability of models, and the links between terrestrial and aquatic systems. Second, scientists and managers can benefit because they are given information about the geographic patterns in ecosystems. Consequently, they are in a better position to design sampling networks, transfer knowledge, and analyze ecosystem diversity.

  • Bailey, Robert G. 1988. Ecogeographic analysis. USDA Forest Service Misc Publication 1465. USDA Forest Service, Washington, DC. 16 pp.

Ecological units of different sizes for predictive modeling of resource productivity and ecological response to management need to be identified and mapped. A set of criteria for subdividing a landscape into ecosystem units of different sizes is presented, based on differences in factors important in differentiating ecosystems at varying scales in a hierarchy. Practical applications of such units are discussed.

  • Bailey, Robert G. 1974. Land-capability classification of the Lake Tahoe Basin, California-Nevada. USDA Forest Service Misc Publication. USDA Forest Service and Tahoe Regional Planning Agency, South Lake Tahoe, CA. 32 pp.

The prospect of increased land development in the Lake Tahoe basin emphasizes the need for better criteria for planning and executing development. Land capability classes are established to guide regional planning and development. Land tolerance is used as the principal measure of capability. Two types of factors are used to rate capability or tolerance: soil type and geomorphic setting. The type and intensity of land use consistent with natural limitations are suggested for each capability class. Limits on land-surface modification are expressed as a percentage of each area that can be used for impervious cover.

Working Papers

  • Bailey, Robert G. 2006. Ecoregion mapping and boundaries. Briefing paper prepared for a workshop to revise Army Regulation 70-38: Research, Development, Test and Evaluation of Material for Worldwide Military Operational Environments, Yuma Proving Ground, AZ, January 30-February 2.

Ecoregion maps show the earth's surface subdivided into identifiable areas based on macroscale patters of ecosystems. These ecoregions delimit large areas within which local ecosystems recur more of less throughout the region in a predictable pattern. This presentation summarizes the rationale used in identifying ecoregion boundaries on maps of the United States, North America, and the world's continents.

  • Bailey, Robert G. 2006. Ecoregions of the Rocky Mountain Research Station. Briefing paper prepared for a workshop to revise Army Regulation 70-38: Research, Development, Test and Evaluation of Material for Worldwide Military Operational Environments, Yuma Proving Ground, AZ, January 30-February 2.

This paper explains, describes, and displays the ecosystem-based regions of the Rocky Mountain Research Station. Ecoregions are identified at three hierarchical levels of detail—domain, division, and province—based primarily on climatic conditions and on the prevailing plant formations determined by those conditions. The third level may include additional criteria, for instance altitude variation within climate types. These regions are based on an explicit approach in which regions are differentiated on the basis of comparable likeness and differences.

This article addresses patterns of ecosystems within a region and what these patterns signify in terms of the processes that create them, and it goes on to explain their relevance to design of sustainable landscapes. Until recently, few landscape designers have explored the underpinnings of regional landscape design. Understanding the pattern of sites and the processes that shape them provides design inspiration for urban and suburban landscapes that are in harmony with the region they are embedded within.

  • Bailey, Robert G. 2004. Changing ecoregional map boundaries. Discussion paper. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO. 5 pp.

The Forest Service has developed a mapping framework to help managers better understand the hierarchical order of the ecosystems they manage, the National Hierarchical Framework of Ecological Units. Broad-scale ecoregions (domain, division, and province) and subregions (sections) have been mapped. A team has been working to complete the hierarchy by identifying subsections. This paper presents an evaluation of this idea and gives recommendations.

  • Bailey, Robert G. 2004. Role of landform in differentiation of ecosystems at the mesoscale (landscape mosaics). Discussion paper. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO. 22 pp.

A map showing the upper four levels of Ecomap down to the section level has been published for the entire United States, based on macroclimatic conditions and plant formations. Within the same macroclimate, broad-scale landforms break up the climatic pattern that would occur otherwise and provide a basis for further differentiation of mesoscale ecosystems, known as landscape mosaics. This paper suggests how different levels of landform differentiation could be correlated with landscape mosaics at different levels of resolution.

  • Bailey, Robert G. 2004. A suggested way to improve the subsection mapping process. Discussion paper. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO. 9 pp.

A map showing the upper four levels of Ecomap down to the section level has been published for the entire United States. A national team is working to complete a map of the fifth level, termed subsection. The resulting subsection map appears problematic both in terms of the underlying rationale and in terms of conflict with preexisting maps of the upper levels of Ecomap. An alternative route is suggested that builds on existing approaches used to delineate sections on the published map.

  • Bailey, Robert G. 2003. Ecological climate classification. Discussion paper. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO. 3 pp.

Information about climate is fundamental to an assessment of the land’s capability and suitability for various kinds of use. Areas of uniform climate are also used to identify ecosystem units because climate acts as the primary input of energy and moisture into the system. As the climate changes, the kinds and patterns of dominant life forms of plants and animals change, as do the kinds of soils. Ecosystems of different climates differ significantly.


  • Bailey, Robert G. 2009. Ecoregion-based mapping of military operating environments. Presentation given at the annual meeting of the Association of American Geographers, Boston, MA, April 15-19.

A new map of Military Operating Environments (MOE) was developed from a world-wide ecoregional classification system that is based on climatic conditions and the prevailing vegetation determined by those conditions. This map allows for identification of operational environments across the globe that are analogous to those U.S. Army installations where training and testing of soldiers and equipment take place. Forty major U.S. Army installations were described by their MOE classification. It was determined that there are numerous installations that reside in hot continental and subtropical climates, as well as tropical/subtropical and temperate deserts. There is significant lack of adequate training and testing land resources in the Mediterranean, savanna, and rainforest environments.

  • Bailey, Robert G. 2007. A genetic approach to mapping ecosystems. Presentation given at the annual meeting of the Association of American Geographers, San Francisco, CA, April 17-21.

Criteria for delineating ecosystems on a scale-related basis are presented, based on the processes that operate from the regional scale (ecoregion) to the local, site scale. The units derived from this approach are termed genetic, in that they are predicated upon an understanding of the causal processes that control the pattern of ecosystems. Appreciating spatial relationships between causal mechanisms and resultant patterns is a key to understanding ecosystem dynamics and how they respond to management.

  • Bailey, Robert G. 2006. Ecosystem patterns and their relevance to research and management. Presentation slides. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO.

This presentation discusses the origins of ecosystem patterns from ecoregion to local scale. It describes how understanding these patterns can help scientists and managers in two ways. First, the local systems are shown within context of larger systems. This perspective can be applied in assessing the connections between action at one scale and effect at another, the spatial transferability of models, and the links between terrestrial and aquatic systems. Second, they are given information about the geographic patterns in ecosystems. Consequently, they are in a better position to design sampling networks, transfer knowledge, and analyze ecosystem diversity. The approach illustrates an alternative to single-phenomena and single-scale approaches and indicates the trend toward integration of factors in classifying and analyzing ecosystems at multiple scales.

  • Bailey, Robert G. 2006. Marine ecoregions. Presentation slides. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO.

Oceans occupy some 70 percent of the Earth's surface. Understanding continental systems requires a grasp of the enormous influence that marine systems exert on terrestrial climatic patterns and thus the character and distribution of continental ecoregions. The intent of this paper is to analyze factors affecting the distribution of the Earth’s major marine ecoregions. The objective is to go beyond empirical description by suggesting mechanisms that are responsible for producing the world pattern. Ecoregions recur in similar form in various parts of the world. Because of this predictability, we can transfer knowledge gained about one region to another.

  • Bailey, Robert G. 2005. Fire regimes in different regional ecosystems and their management implications. 2005. Presentation given at the annual meeting of the Association of American Geographers, Denver, CO, April 5-9.

The majority of American forest and grassland ecosystems are adapted to fire of varying frequencies and magnitudes. Fire-excluded systems are prone to changes in composition and density, and are susceptible to catastrophic fire and invasion by non-native species. Planning for fire and land management must incorporate an improved understanding of fire regimes. This paper discusses fire regimes of different ecosystems at the scale of ecoregion, and explores how understanding fire regimes at this scale can abate the threat of fire exclusion and restore fire-adapted ecosystems.

  • Bailey, Robert G. 2004. Ecogeographic analysis. Presentation slides. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO.

This presentation outlines a system that subdivides the Earth into a hierarchy of increasingly finer-scale ecosystems. The system consists of a three-part, nested hierarchy of ecosystem units and associated mapping criteria. Delineating units involves identifying the environmental factors controlling the spatial geography of ecosystems. Macroscale units (ecoregions) are climatically controlled and delineated as Koppen-Trewartha climate zones. Nested within these are landscape mosaics, the mesoscale units, controlled by landform and delineated by Hammond's landform regions.

  • Bailey, Robert G. 2004. Understanding regional ecosystem patterns to design monitoring networks and sustainable landscapes. Presentation given at the Monitoring Science and Technology Symposium, Denver, CO, September 20-24.

An ecoregion is a large area of similar climate where similar ecosystems occur on similar sites. This presentation describes the processes that shape local ecosystem patterns, and goes on to explore how understanding the patterns of a particular region is import for design of (1) sampling networks for monitoring ecosystems, and (2) sustainable landscape-scale management.

  • OFFICIAL NAME: United States of America
  • FORM OF GOVERNMENT: Constitution-based federal republic
  • CAPITAL: Washington, D.C.
  • POPULATION: 330,175,936
  • LANGUAGES: English, Spanish (no official national language)
  • MONEY: U.S. dollar
  • AREA: 3,794,083 square miles (9,826,630 square kilometers)
  • MAJOR MOUNTAIN RANGES: Rocky Mountains, Appalachian Mountains
  • MAJOR RIVERS: Mississippi, Missouri, Colorado


The United States of America is the world's third largest country in size and nearly the third largest in terms of population. Located in North America, the country is bordered on the west by the Pacific Ocean and to the east by the Atlantic Ocean. Along the northern border is Canada and the southern border is Mexico. There are 50 states and the District of Columbia.

More than twice the size of the European Union, the United States has high mountains in the West and a vast central plain. The lowest point in the country is in Death Valley which is at -282 feet (-86 meters) and the highest peak is Denali (Mt. McKinley) at 20,320 feet (6,198 meters).

Map created by National Geographic Maps


Throughout its history, the United States has been a nation of immigrants. The population is diverse with people from all over the world seeking refuge and a better way of life.

The country is divided into six regions: New England, the mid-Atlantic, the South, the Midwest, the Southwest, and the West. European settlers came to New England in search of religious freedom. These states are Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont.

The mid-Atlantic region includes Delaware, Maryland, New Jersey, New York, Pennsylvania, and the city of Washington, D.C. These industrial areas attracted millions of European immigrants and gave rise to some of the East Coast's largest cities: New York, Baltimore, and Philadelphia.

The Midwest is home to the country's agricultural base and is called the "nation's breadbasket." The region comprises the states of Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin.

The Southwest is a beautiful stark landscape of prairie and desert. The states of Arizona, New Mexico, Oklahoma, and Texas are considered the Southwest and are home to some of the world's great natural marvels, including the Grand Canyon and Carlsbad Caverns.

The American West, home of rolling plains and the cowboy, is a symbol of the pioneering spirit of the United States. The West is diverse, ranging from endless wilderness to barren desert, coral reefs to Arctic tundra, Hollywood to Yellowstone. The states of the West include Alaska, Colorado, California, Hawaii, Idaho, Montana, Nevada, Oregon, Utah, Washington, and Wyoming.


The landscape varies across the large country from tropical beaches in Florida to peaks in the Rocky Mountains, from rolling prairie lands and barren deserts in the West to dense wilderness areas in the Northeast and Northwest. Interspersed throughout are the Great Lakes, the Grand Canyon, the majestic Yosemite Valley, and the mighty Mississippi River.

The wildlife is as diverse as the landscape. Mammals such as bison once roamed freely across the plains, but now live only in preserves. Black bears, grizzlies, and polar bears are the largest carnivores. There are over 20,000 flower species and most came from Europe. There are more than 400 areas which are protected and maintained by the National Park Service, and many other parks in each state.

The bald eagle is the national bird and symbol of the United States and is a protected species.


Citizens over the age of 18 years old vote to elect the President and Vice President of United States every four years. The president lives in the White House in the capital city of Washington, D.C.

There are two houses of Congress: the Senate and the House of Representatives. There are 100 senators, two from each of the 50 states and each serves a six-year term. There are 435 representatives who must be elected every two years.

The Supreme Court is made up of nine justices who are picked by the president and must be approved by Congress.

For the first time in the nation's history an African American, Barack Obama, was elected President of the United States in 2008. He was reelected for a second term in 2012.

Advances in the past hundred years have established America as a world leader economically, militarily, and technologically. America has the largest coal reserves in the world.


For centuries native peoples lived across the vast expanse that would become the United States. Starting in the 16th century, settlers moved from Europe to the New World, established colonies, and displaced these native peoples.

Explorers arrived from Spain in 1565 at St. Augustine, Florida, and the British landed in 1587 to establish a colony in Roanoke, in present-day Virginia. In 1606 another British colony was established in what would become Jamestown, Virginia. From there, the French founded Quebec in 1608, then the Dutch started a colony in 1609 in present-day New York. Europeans continued to settle in the New World in ever-increasing numbers throughout the next couple of centuries.

Conflict with the Native Americans

While Native Americans resisted European efforts to gain land and power, they were often outnumbered and didn&rsquot have as powerful of weapons. The settlers also brought diseases that the native peoples had not faced before, and these illnesses sometimes had horrible effects. A 1616 epidemic killed an estimated 75 percent of the Native Americans in the New England region of North America.

During this time, fights between the settlers and Native Americans erupted often, particularly as more people claimed land where the Native Americans lived. The U.S. government signed nearly 400 peace treaties between the mid-18th century and the mid-19th century to try to show they wanted peace with the Indigenous tribes. But the government did not honor most of these treaties, and even sent military units to forcibly remove Native Americans from their lands.

For example, in 1830, President Andrew Jackson signed the Indian Removal Act, which granted land west of the Mississippi River to Native American tribes who agreed to give up their lands. But this broke with other treaties he had signed with Native American tribes in the Southeast. The removal was supposed to be voluntary, but Jackson used legal and military action to remove several tribes from their homelands and ended nearly 70 treaties during his presidency.

By the mid-19th century, most Native American tribes had been wiped out or moved to live on much smaller portions of land in the Midwest.

Declaring Independence

In 1776, colonists living in the New England area of the New World drafted the Declaration of Independence, a document that stated that the American colonies were tired of being ruled by Great Britain (now called the United Kingdom). The settlers fought for&mdashand won&mdashtheir independence and formed a union of states based on a new constitution. But despite stating that &ldquoall men are created equal&rdquo in the Declaration of Independence, the new country was home to millions of enslaved people.

Slavery in the United States

Enslaved Africans were brought to North America by boat as early as 1619. The trans-Atlantic slave trade saw more than 12.5 million people kidnapped from Africa and sold at ports throughout the Americas over the next couple of centuries.

By 1860, nearly four million enslaved people lived in the country. Most worked in the South, where their free labor allowed the sugar, cotton, and tobacco industries to flourish. Enslaved people even built the White House and the U.S. Capitol.

When Abraham Lincoln became president in 1861, the nation had been arguing for more than a hundred years about enslaving people and each state&rsquos right to allow it. Lincoln wanted to end slavery. Many people in the northern states agreed with him some people in the southern states, however, relied on enslaved people to farm their crops and did not want slavery to end. Eventually, 11 southern states formed the Confederate States of America to oppose the 23 northern states that remained in the Union. The Civil War began on April 12, 1861.

The Civil War was fought between abolitionists, or people who wanted to end slavery, and the pro-slavery Confederacy. Enslaved people weren&rsquot freed until Lincoln delivered his famous Emancipation Proclamation speech in 1863, midway through the war. Two years later, the Civil War ended with a Union victory.

That same year, the passage of the 13th Amendment officially abolished the practice of slavery and ended nearly 250 years of slavery in the country. But it did not end racism. Former enslaved people&mdashas well as their descendants&mdashstruggled with discrimination, and African-American heroes today are still fighting for equality.

Progress (and Wars) in the 20th Century

After the Civil War, the United States continued to expand westward until 1890, when the U.S. government declared the West fully explored. During this time of expansion, the population grew from about five million people in 1800 to nearly 80 million people in 1900.

The early 1900s were a time of progress in the United States. This in part was because of the number of immigrants coming to the country looking for opportunity. Between 1900 and 1915, 15 million immigrants arrived in the United States from countries such as Italy, Russia, and Poland. The new citizens worked in places such as gold mines and garment factories, and helped construct railroads and canals. These immigrants brought new ideas and culture to the young country.

The 20th century was also a time of industrial advancement. The development of the automobile and the airplane lead to an increase in factory jobs and marked a shift in more people moving to live and work in big cities instead of farming in small towns.

But there were tough times, too. The United States fought alongside Great Britain, France, Russia, Italy, Romania, and Japan against Germany, Austria-Hungary, Bulgaria, and the Ottoman Empire (now the country of Turkey) in World War I, before the country suffered through what became known as the Great Depression, a time of economic crisis during the 1930s.

In the 1940s, then-president Franklin Delano Roosevelt steered the country out of the Depression before leading the country during the Second World War, alongside allies France, Great Britain, and the Soviet Union (now Russia), against Germany, Italy, and Japan.

The United States&rsquo reputation as a progressive country took hold after the two World Wars and the Great Depression. The &rsquo50s, &rsquo60s, and &rsquo70s were a time of innovation in the nation. In 1958, NASA&mdashthe National Aeronautics and Space Administration&mdashstarted exploring the possibility of space flight. By 1969, the agency landed the first human on the moon.

Throughout these three decades, the fight for civil rights in the country continued with Americans of all backgrounds fighting for equal rights for their fellow citizens. Civil rights leader Martin Luther King, Jr.&rsquos &ldquoI Have a Dream&rdquo speech is perhaps the most famous speech associated with the civil rights movement. Historic firsts for people of color during these decades include Dalip Singh Saund becoming the first Asian American elected to the Congress in 1957 Thurgood Marshall becomingthe first African-American justice to serve on the Supreme Court in 1967 and Shirley Chisholm becoming the first African- American female elected to Congress in 1968.

The late 1900s saw the U.S. government get involved in several wars on different fronts, including the Vietnam War, a war between what was then the two separate countries of North and South Vietnam, in which the United States sided with South Vietnam the Cold War, a long period of non-violent tensions between the United States and the former Soviet Union, now Russia and the Gulf War, a war waged by 30-plus nations lead by the United States against the country of Iraq.

An Attack on America

Although the country was still a relatively young nation at the beginning of the 21st century, the United States had established itself as a global power. Some people saw this power as a threat.

On September 11, 2001, 19 terrorists who disagreed with the United States&rsquo involvement in world affairs hijacked four planes. Two of the planes were flown into the two 110-story skyscrapers that made up New York City&rsquos World Trade Center. Another crashed into the Pentagon outside of Washington, D.C. The fourth plane went down in a Pennsylvania field. Nearly 3,000 people died that day.

Then-president George W. Bush sent troops to Afghanistan after the events of 9/11. He hoped to capture those responsible for the attacks, including al Qaeda terrorist leader Osama bin Laden. Bush also sent troops to Iraq in 2003, after rumors started that the country was hiding dangerous weapons that the president wanted to find and destroy.

While bin Laden was eventually located and killed in 2011, the United States is still fighting what&rsquos called &ldquothe war on terrorism&rdquo today.

Historic Firsts&mdashPlus, a Pandemic

The 21st century marked more progress for the United States, particularly at its highest levels of government. In 2008, Barack Obama became the first African American to be elected president of the United States. In 2020, Kamala Harris became the first Black and Indian American person and the first woman elected vice president.

The Applied Use of Accounting Information Systems

Moving beyond financial statements to the precise numbers needed to make sound decisions requires the ability to manipulate data. As used here, data manipulation means to extract what matters most and then apply the correct accounting principles needed to deliver the most accurate financial picture possible to make fully informed business decisions.

Accounting software is widely available and used by businesses of all sizes. Small businesses commonly use QuickBooks or Peachtree to help them with their accounting functions. These tools allow them to record all of their financial transactions and create statements with only a few clicks. Larger businesses will want expanded functionality. Commercial software is available, and is be required to perform many functions:

Technical Validation

The data were validated in two steps. First, as described in the methods section, filters were applied during the processing to exclude catchments with regulation structures, with poor (or nonexistent) watershed boundaries, too few hydrometric data points and by carefully indicating that some watershed boundaries were extracted from GSIM instead of from an official agency dataset.

Second, the data were displayed on maps to show the similarities and differences between the various datasets and to allow comparison to atlases and other knowledge bases. Figure 2 shows the comparison of the 6 precipitation databases (all except the non-quality-controlled stations). It can be seen that all datasets show the same patterns across North America. Similar comparisons were performed on North America in another study on approximately 3000 catchments and obtained maps that are very similar to the ones in Fig. 2 11 . All datasets clearly show the high west-coast precipitation patterns and the drier Midwest and Canadian prairies.

Comparison of average annual precipitation depths in the HYSETS catchments across North America. Precipitation data from the six data sources are displayed in millimetres. The data sources are the station data (top left), SCDNA (top right), NRCan (center left), Livneh (center right), ERA5 (bottom left) and ERA5-Land (bottom right).

Figure 3 shows a similar comparison for daily average temperature. The north-south gradient as well as the high-elevation gradients in the mountain ranges of the Western United States and Canada are clearly seen. There are some small differences between the different products when observing in detail, which corresponds to the various product data sources. These findings are true for all the temperature datasets in this database.

Comparison of average daily temperature in the HYSETS catchments across North America. Temperatures from the six data sources are presented in degrees Celsius. The data sources are the station data (top left), SCDNA (top right), NRCan (center left), Livneh (center right), ERA5 (bottom left) and ERA5-Land (bottom right).

Figure 4 presents the average maximum annual SWE amounts over the dataset region. Again, these values represent well the expected values for North America, with no snow in the southern parts of North America and more snow in the North and mountain ranges. Extents are limited by the SNODAS original extents in the top panel and cover the entire domain with the ERA5-Land product in the bottom panel.

Average annual maximum snow water equivalent amount in the HYSETS catchments across North America. The snow water equivalent is taken from the SNODAS database (top panel) which extends up to 54°N latitude and from ERA5-Land (bottom panel) which covers the entire domain.

Finally, the watershed properties were analyzed and mapped to obtain a visual confirmation of the various fields. Figure 5 presents watershed-averaged values of elevation, slope, soil permeability and porosity and land use fractions for forests and croplands. It can be seen that elevations map well with the actual topography of North America and that the mountainous regions show higher average slopes, as expected. Porosity and permeability are more variable in nature but reflect the data present in the GLHYMPS subsoil dataset. Finally, land cover fractions are also as expected, with large portions of the United States Midwest having cropland as the dominant land use category and major forested areas in Canada, north-east United States and Western United States. Figure 5 also shows that the Mexican catchments are highly heterogeneous in terms of physiographic attributes 40 .

A selection of average watershed properties in the HYSETS catchments across North America. The data presented include elevation (top left), slope (top right), permeability (center left), porosity (center right), forest fraction (bottom left) and cropland fraction (bottom right).

Finally, the Global Streamflow and Indices Metadata (GSIM) database 21 found approximately 15750 stations in North America that were of high enough quality to be included. The HYSETS database independently found 14425 catchments of high quality from a total number of over 25000 initially available. This gives confidence that the verification methods and filters put in place allowed a similar cut-off to those in the GSIM database.

Ecological Services

The Mountain-Prairie Region's Office of Ecological Services (ES) works to restore and protect healthy populations of fish, wildlife, and plants and the environments upon which they depend. Using the best available science, ES personnel work with Federal, State, Tribal, local, and non-profit stakeholders, as well as private land owners, to avoid, minimize, and mitigate threats to our Nation's natural resources.

Hard ticks (Ixodidae)

Hard ticks (Ixodidae) begin as an egg that is laid by an adult female tick. Once the egg hatches a larva emerges that must then find and feed on a small mammal or bird (host). After feeding it drops to the ground from the host and goes through a molting process, emerging as a nymph.

Nymphal hard ticks then seek larger hosts, and after feeding drop off and molt into adults. The life cycle of hard ticks lasts one to two years depending on the species. The bite of a hard tick is generally painless, with a feeding process lasting several hours, to days, even weeks.


Nissan Canada Inc. (NCI) is the Canadian sales, marketing and distribution subsidiary of Nissan Motor Limited and Nissan North America, Inc. NCI was the first Japanese-based automaker to incorporate in Canada in 1965, and now directly employs more than 300 full-time staff across offices in Vancouver (BC), Mississauga (ON), and Kirkland (QC). There are 210 independent Nissan dealerships, including 126 that are also electric vehicle-certified dealers, and 38 INFINITI retailers across Canada.

More information about Nissan in Canada and the complete line of Nissan and INFINITI vehicles can be found online at and

Nissan Canada Inc.
5290 Orbitor Drive
Mississauga, Ontario
L4W 4Z5 Canada
Phone: (905) 629-2888
Fax: (905) 629-9742

Nissan Canada Finance

Nissan Canada Finance (NCF), offers financial solutions for its dealers and customers through various wholesale and retail lending programs, aimed at exceptional customer value. NCF also continuously invests and supports the network with tools and training to deliver a seamless ownership experience for all customers.

Nissan Canada Finance
5290 Orbitor Drive
Mississauga, Ontario
L4W 4Z5 Canada
Phone: (905) 602-0792
Fax: (800) 265-0835

Nissan Design America

Nissan Design America (NDA) began as Nissan Design International in 1979 in San Diego, established as a satellite studio for Nissan Motor Co., Ltd. Its original mission was to provide a local perspective on the North American market and generate innovative ideas and design. After 40 years in operation, NDA is now a full-production automotive design studio capable of handling all phases of automotive design development, from exploratory to production. NDA also has had design support operations in Silicon Valley (California, U.S.) since 2013.

NDA is part of the Global Nissan Design organization led by Alfonso Albaisa, Senior Vice President of Global Design for Nissan Motor Co., Ltd. The global organization consists of NDA, Nissan Global Design Center (NGDC, Atsugi, Japan), Creative Box, Inc. (Tokyo, Japan), Nissan Design Europe (London), Nissan Design China (Shanghai, China) and small design offices in India, Thailand and Brazil.

NDA designs vehicles with emphasis on the Americas region with sensitivity for the global market, in close collaboration with its counterparts at NGDC and Nissan Technical Centers in Japan and North America. NDA's recent contribution includes the all-new 2019 Altima, Maxima and Murano refresh, Titan full-size truck, as well as Nissan IMs concept which debuted at the 2019 North American International Auto Show.

Nissan Design America
9800 Campus Point Drive
San Diego, CA 92121
Phone: (858) 457-4400

Nissan Mexicana, S.A. de C.V., (NMEX), was established in 1961 as an importer and distributor of Datsun vehicles. In 1966, NMEX became the first Japanese-owned automobile production facility in North America. Since then, the company has exported more than 5 million vehicles, including the Sentra and Versa for North America. Today, with an annual vehicle manufacturing capacity of more than 800,000, NMEX’s three manufacturing facilities produce vehicles, engines and other parts for global distribution, making it the largest car manufacturer and exporter in the country. NMEX has more than 14,500 employees in all of its manufacturing, distribution, R&D and corporate facilities. Since 2009, Nissan has been the best-selling brand in the country with a market share of over 25 percent.

Nissan Mexicana, S.A. de C.V.
Ave. Insurgentes Sur 1958 - 11piso
Col. Florida
C.P. 01030, Mexico, D.F.
Phone: (5) 6-28-27-27
Fax: (5) 6-28-26-96

Nissan Motor Acceptance Company

Nissan Motor Acceptance Company (NMAC), including its Infiniti Financial Services (IFS) division, is the automotive financial services arm of Nissan North America. Established in 1981, NMAC's primary emphasis is to provide purchase and lease financing for the complete line of Nissan and Infiniti vehicles to consumers throughout the United States. The company offers financing for the complete line of Nissan and Infiniti vehicles sold in the United States.

NMAC's Customer Center in Dallas, Texas, is responsible for all credit services, customer service operations, and support functions. NMAC's Franklin, Tennessee, office, which is the company's headquarters, is responsible for marketing, finance, accounting, and re-marketing (the disposition of off-lease, fleet, credit, and corporate vehicles). NMAC Regional Financial Services Managers offer information about NMAC's financial products and programs to over 1,250 Nissan and Infiniti dealers nationwide.

NMAC Customer Center
8900 Freeport Parkway
Irving, TX 75063
Phone: (214) 596-4000

Nissan first came to the United States to sell vehicles in 1958 and began importing and making Datsun vehicles in the United States under the Nissan Motor Corporation in U.S.A. (NMC), name in 1960. In 1990, Nissan North America Inc. (NNA), was created to coordinate all of Nissan's various activities in North America to enhance the design, development, manufacturing, and marketing of Nissan vehicles. In 1998, the two organizations merged operations under the Nissan North America, Inc., name. Headquartered in Franklin, Tennessee, Nissan's North American operations include automotive styling, engineering, consumer and corporate financing, sales and marketing, distribution and manufacturing for the United States, Canada, and Mexico.

Nissan North America Inc.
One Nissan Way
Franklin, TN 37067
Phone: (615) 725-1000

Nissan North America - U.S. Manufacturing

Nissan has four manufacturing facilities in the U.S. - in Smyrna and Decherd, Tennessee, and Canton, Mississippi. Production at Nissan's Smyrna Vehicle Assembly Plant began in June 1983. The Smyrna plant, the highest-volume vehicle assembly plant in North America, has an annual production capacity of 640,000 vehicles and produces the Nissan Altima, Maxima, LEAF, Rogue, Pathfinder and INFINITI QX60.

The vehicle assembly plant in Canton, Mississippi, began producing vehicles in May 2003. The plant has an annual production capacity of 450,000 vehicles and produces the Nissan Altima, Frontier, TITAN, Murano and NV Cargo and Passenger Vans.

Nissan's powertrain assembly plant in Decherd, Tennessee began production in May 1997. Today the plant manufactures all engines for the complete lineup of Nissan and INFINITI vehicles produced in the U.S. The plant also forges crankshafts and cylinder block castings.

INFINITI’s powertrain assembly plant in Decherd, Tennessee, began production in June 2014. The plant assembles 2.0-liter 4-cylinder gasoline engines for the INFINITI Q50 sports sedan and Mercedes-Benz C-Class and their derivatives. The 310,000-square foot facility was developed as a collaboration between the Renault-Nissan Alliance and Daimler AG.

Nissan Smyrna Vehicle Assembly Plant
983 Nissan Drive
Smyrna, TN 37167
Phone: (615) 459-1400

Nissan Canton Vehicle Assembly Plant
300 Nissan Drive
Canton, MS 39046
Phone: (601) 855-6010

Nissan Decherd Powertrain Plant
520 Nissan Powertrain Drive
Decherd, TN 37324
Phone: (931) 962-5000

INFINITI Decherd Powertrain Plant
520 Nissan Powertrain Drive
Decherd, TN 37324
Phone: (931) 962-5000

Nissan Technical Center North America

Nissan Technical Center North America (NTCNA) is responsible for blending technology and engineering to create cars that deliver total customer satisfaction. This process involves interaction and cooperation among all technical departments, which results in "total vehicle development."

NTCNA has a proving ground facility located on 3,050 acres in Stanfield, Arizona. Arizona's low desert terrain provides NTCNA with an ideal environment to test Nissan vehicles for hot weather, heat durability, engine cooling and air conditioner performance. The NTCNA proving ground also features a 5.7 mile high-speed oval and four individual road courses designed to test vehicle durability, reliability, and ride comfort.

NTCNA employs over 1,200 people and represents an investment of $238 million. NTCNA has operations at the following locations:

  • Nissan Technical Center North America – Farmington Hills, MI
  • Nissan Research Center Silicon Valley – Sunnyvale, CA
  • Arizona Test Center – Stanfield, AZ
  • e-Powertrain Technical Affairs and Testing Center – West Sacramento, CA
  • Nissan Design America – San Diego, CA

Nissan Technical Center North America
39001 Sunrise Drive
Farmington Hills, MI 48333-9200
Phone: (248) 488-4123
Fax: (248) 488-3901

North American Migration Flyways

The routes followed by migratory birds are numerous, and while some of them are simple and easily traced, others are extremely complicated. Differences in distance traveled, in time of starting, in speed of flight, in geographical position, in the latitude of the breeding and wintering grounds and in other factors all contribute to great diversity. No two species follow exactly the same path from beginning to end geographical groups of species with an almost continental distribution may travel different routes.

Bird migration is generally thought of as a north-and-south movement, with the lanes of heavier concentration following the coasts, mountain ranges and principal river valleys. In general, it may be said that the great routes of migration do conform very closely to major topographical features when these happen to lie in the general direction of the travel to be performed. It happens to work out nicely in North America where the coasts, mountain chains and come of the larger rivers do not depart from a north-and-south alignment.

The terms “migration route” and “flyway” are to some extent theoretical concepts, while the latter has, in addition, come to have an administrative meaning. Migration routes may be defined as the lanes of individual travel from any particular breeding ground to the winter quarters of the birds that use them. Flyways, on the other hand, may well be conceived as those broader areas in which related migration routes are associated or blended in a definite geographic region. They are wide arterial highways to which the routes are tributary.

There are four (4) major North American flyways that have been named the Atlantic, the Mississippi, the Central and the Pacific Flyways. Except along the coasts, the flyway boundaries are not always sharply defined and both in the northern breeding, and the southern wintering, grounds there is more or less overlapping. As a matter of fact, in the region of Panama, parts of all four flyways merge into one.

Atlantic Flyway:

The Atlantic Flyway may be described as extending from the offshore waters of the Atlantic Coast west to the Allegheny Mountains where, curving northwestward across northern West Virginia and northeastern Ohio, it continues in that direction across the prairie provinces of Canada and the Northwest Territories to the Arctic Coast of Alaska. The flyway embraces several primary migration routes and many more that are important as tributaries, some of the latter being branches from primary routes of other flyways. The Atlantic Flyway route from the northwest is of great importance to migratory waterfowl and other birds some of which are flocks of Canvasbacks, Redheads and Lesser Scaups that winter on the waters and marshes south of Delaware Bay. The coastal route of the Atlantic Flyway, which in general follows the shore line, has its northern origin in the eastern Arctic islands and the coast of Greenland. This is a regular avenue of travel, and along it are many famous points for the observation of migrating land and water birds.

There is one route (not shown in image) that may be considered although it is so exclusively oceanic that it is included under “Pelagic Migration.” This lane of travel passes directly over the Atlantic Ocean from Labrador and Nova Scotia to the Lesser Antilles, and across a group of small islands to the mainland of South America. It is not known to be used by any of the smaller land birds, but is followed by thousands of water birds and by shore birds of several species. Since it lies over the sea, this route is definitely known only as its terminals and from occasional observations that have been made in Bermuda and the Antilles. In the autumn, some of the shore birds that nest on the Arctic tundra of Mackenzie and Alaska fly southeastward across Canada to the Atlantic coast and finally follow this oceanic course to the mainland of South America.

Many of the birds that breed east of the Allegheny Mountains parallel to seacoast, move southwestward in fall, a direction they apparently maintain from northwestern Florida, crossing the Gulf to the coastal regions of eastern Mexico where they have a land route for the balance of the journey. A more direct route involving even longer flights lies directly across the Caribbean Sea, but despite that fact it is used almost entirely by land birds. After taking off from the coast of Florida, the migrants on this route find only two land masses in their course where they can pause for rest and food. Over 60 species cross the 150 miles from Florida to Cuba, where about half of them remain for the winter. Others fly the additional 90 miles between Cuba and Jamaica. From that point to the South American coast, there is a stretch of unbroken ocean 500 miles across, and scarcely a third of the North American migrants leave the forested mountains of Jamaica to risk the perils of this ocean trip.

Mississippi Flyway:

This flyway is relatively simple although it presents some features of interest, chiefly as they affect the migratory waterfowl. It’s eastern boundary runs through the peninsula of southern Ontario to western Lake Erie, then southwestwardly across Ohio and Indiana to the Mississippi where it rather closely follows the river to its mouth. The western boundary does not have such precise definition as the eastern boundary, and for this reason in eastern Nebraska and western Missouri and Arkansas the Mississippi Flyway merges imperceptibly into the Central Flyway. The longest migration route of any in the Western Hemisphere lies in this flyway. It’s northern terminus is on the Arctic coast of Alaska and its southern end in Patagonia. During the spring migration some of the shorebirds traverse the full length of this great artery and several species that breed north to Yukon and Alaska must twice each year cover the larger part of it. For more than 3000 miles, from the mouth of the Mackenzie to the delta of the Mississippi, this route is uninterrupted by mountains. There is not even a ridge of hills on the entire route that is high enough to interfere with the movements of migrating birds, and the greatest elevation above sea level is less than 2000 feet. Well timbered and watered, the entire region affords ideal conditions for the support of hosts of migrating birds. The two rivers that mark it, the Mackenzie emptying on the Arctic coast and the Mississippi in the Gulf of Mexico, have a general north-and-south direction, another factor in determining the importance of this route which is used by large numbers of ducks, geese, shorebirds, blackbirds, sparrows, warbler and thrushes,

The majority of North American land birds, seeking winter homes in the tropics, that come south through the Mississippi Flyway take the short cut across the Gulf of Mexico in preference to the longer, though presumably safer, land or island journey by way of Texas or the Antilles. During the height of migration some of the islands off the coasts of Louisiana and Texas are wonderful observation places.

It was once thought that most of the North American birds that migrate to Central America made a leisurely trip along the west coast of Florida, crossed to Cuba and then made the short flight from the western tip of that island to Yucatan. The map will suggest this as the most natural route, but as a matter of fact, it is used by only certain swallows and shorebirds, or an occasional individual of some other species that has been driven from its accustomed course.

Central Flyway:

In the United States, the Central Flyway merges toward the east with the Mississippi Flyway and bounded in that direction by the Missouri River. In the south on this side, it runs through western Missouri, Arkansas and Louisiana, and then follows the Gulf coast of Mexico southward. On the northwest Arctic coast, where this great flyway has its beginning, the same territory involved that also sends hosts of migrants down the Mississippi Flyway, but farther south, in Canada, the western boundary follows closely the eastern base of the Rocky Mountains. In western Montana, however, the continental divide is crossed and the line passes through the Great Salt Lake Valley and then somewhat east of south across the tableland of Mexico. It may be called “the flyway of the Great Plains” as it encompasses all of that vast region lying between the valley of the Mississippi River and the Rocky Mountains, the principal wheat-growing region of both Canada and the United States.

On its western boundary is an important breeding area for waterfowl at the northern end of Great Salt Lake, Utah. The Central Flyway is relatively simple, as the majority of the birds that use it make direct north and south journeys from breeding grounds in the North to winter quarters in the South.

Pacific Flyway:

The Pacific Flyway includes the Arctic archipelago as Melville, Banks and Victoria islands from which region the eastern boundary tends to the southwest between Great Bear and Great Slave lakes to the western boundary of the Central Flyway along the eastern base of the Rocky Mountains in Canada. The territory of this flyway, comprises the western Arctic, including Alaska and the Aleutian Islands and the Rocky Mountain and Pacific coast regions of Canada, the United States and Mexico, south to where it becomes blended with other flyways in Central and South America.

The passage of gulls, ducks and other water birds at Point Barrow, Alaska and at other points on the Arctic coast may be the best defined Arctic route in North America. This route across the Alaska Peninsula and the Gulf of Alaska and parallels the coast line of British Columbia, Washington, Oregon and California. The Pacific oceanic route is used by the Arctic Terns that breed in Alaska and those from the more western tern colonies of Canada. The vast delta region of the Yukon River in Alaska is a breeding ground for many species of waterfowl and this area marks the northern terminus for some of those that use the coastal route for most of all of their migratory flights.

The longest and important route of the Pacific Flyway is that originating in northeastern Alaska and passing for most, if not all, of its length through the interior. Most of the waterfowl that travel the United States section of this route come from Alaska and the Mackenzie Valley and other interior areas. Starting in Alaska, Yukon and Mackenzie, this route runs southward through western Alberta. The Pacific Flyway element apparently closely parallels the eastern foothills of the Rocky Mountains. Near the international border, the route branches and while large flights continue southeastward into the Central and Mississippi flyways, others turn southwestward across northwestern Montana and the panhandle of Idaho, follow along the Snake and Columbia River valleys and then turn southward across central Oregon to the interior valleys of California. Suitable winter quarters for birds are found in California from the Sacramento Valley south to Salton Sea and in the tidal marshes near San Francisco Bay.

The southward route of migratory land birds of the Pacific Flyway that in winter leave the United States extends through the interior of California to the mouth of the Colorado River and on to the winter quarters that are principally in western Mexico.

Watch the video: Cadastral surveying -part1-surveyor trade-2nd year students