Download PHYSICAL REGIONS OF THE UNITED STATES

PHYSICAL REGIONS OF THE UNITED STATES
North America is the world’s third largest continent. It is surrounded on three sided by oceans: the Atlantic
Ocean to the east, the Pacific Ocean to the west, and the icy Arctic Ocean to the north. To the south, an
isthmus, or narrow strip of land, links North America to South America.
The United States is one of the largest countries in the world. Its physical region offer great contrasts.
In some regions, the land is fertile. Other regions have natural resources such as coal and oil.
Geographers divide the United States into different physical regions marked by contrasting landforms
and physical features.
PACIFIC COAST The westernmost region of North America is the pacific Coast. It includes high mountain
ranges that stretch from Alaska to Mexico. In the United States, some of these western ranges are near the
Pacific Ocean. The Cascades and the Sierra Nevada stand a bit farther inland. Important cities of the Pacific
Coast region include Seattle, Portland, San Francisco, San Diego, and Los Angeles.
A notable feature of the Pacific Coast region is the San Andreas Fault. This 600-mile fracture in the
Earth’s crust runs through California from northwest to southeast. Movement of the Earth’s crust along this
fault can cause earthquakes. For example, powerful quakes shook San Francisco in 1906 and Los Angeles in
1994, causing significant damage and loss of life.
INTERMOUNTAIN REGION East of the Pacific Coast mountain ranges lies the Intermountain Region. This
region is marked by mountain peaks, high plateaus, deep canyons, and dry, sandy deserts. The Grand Canyon,
more than a mile deep, cuts through the Intermountain Region. Another prominent physical feature is the Great
Salt Lake of Utah, the nation’s largest saltwater lake.
The rugged terrain limits where people can live in the Intermountain Region. Among the few major
cities located there are Phoenix and Salt Lake City.
ROCKY MOUNTAINS The Rocky Mountains stretch from Alaska through Canada into the western United
States. They include the Bitteroot Range in Idaho and Montana, the Big Horn Mountains in Wyoming, and
Sangre de Cristo Mountains in Colorado and New Mexico. In Mexico, the Rockies become the Sierra Madre,
or “mother range.”
The Rockies include some of the highest peaks in North America – some with an elevation, or height
above sea level, of more than 14,000 feet. Throughout history, visitors like Katharine Lee Bates have marveled
at the beauty and grandeur of the Rocky Mountains. Today, Denver is a major city of the Rocky Mountain
Region.
INTERIOR PLAINS Between the Rockies in the West and the Appalachian Mountains in the East is the large
lowland area called the Interior Plains. The dry western part of the region is called the Great Plains. The
eastern part is called the Central Plains.
Scientists believe that a great inland sea once covered the Interior Plains. Today, some parts are rich in
resources such as coal and petroleum. Other parts offer fertile soil for farming and grasslands for raising cattle.
Major cities of the Interior Plains include Dallas, St. Louis, Chicago, Cincinnati, Detroit, and Indianapolis.
OZARK HIGHLANDS The Ozark Highlands extend across southern Missouri and northern Arkansas and into
eastern Kansas. Thick with forests, the region includes mountains that rise more than 2,000 feet. The highest
are the Boston Mountains in Arkansas. Important industries in the region include forestry, agriculture, and
mining.
APPALACHIAN MOUNTAINS The Appalachian Mountains run along the eastern part of North /America.
They stretch from Canada in the North to Georgia and Mississippi in the South. The Appalachians have
different names in different places. For example, the Green Mountains, Alleghenies, and Great Smoky
Mountains are all part of the Appalachians.
The Appalachians are lower and less rugged than the Rockies. The highest peak is Mt. Mitchell in
North Carolina, with an elevation of 6,684 feet. Today, hearty hikers enjoy the challenge of walking the
Appalachian Trail from Georgia to Maine.
CANADIAN SHIELD The Canadian Shield is a lowland area that lies mostly in eastern Canada. The southern
part extends into Michigan, Wisconsin, and Minnesota. This region was once an area of high mountains.
Centuries of erosion, or gradual wearing away, reduced the area to low hills and plains. The Canadian Shield
is rich in minerals.
COSTAL PLAINS The easternmost region of North America is called the Coastal Plains, a fairly flat, lowland
area. This was the first region settled by Europeans who crossed the Atlantic Ocean. It is made up of two sub
regions, the Atlantic Plain and the Gulf Plain.
The Atlantic Plain lies between the Atlantic Ocean and the foothills of the Appalachians. The Atlantic
Plain is narrow in the North, where major cities such as Boston, New York, and Philadelphia are located. It
broadens in the South to include all of Florida.
The Gulf Plain lies along the Gulf of Mexico. This region is economically important because of its large
deposits of petroleum. New Orleans and Houston are major cities of the Gulf Plain.
HAWAIIAN ISLANDS The Hawaiian Islands lie far out in the Pacific about 2,400 miles west of California.
Much of Hawaii has a wet tropical climate and dense tropical rain forest vegetation. The region includes eight
large islands and many smaller ones.
The islands are actually the visible tops of volcanoes that erupted through the floor of the Pacific many
centuries ago. Mauna Loa, on the island of Hawaii, is an active volcano that rises 13,680 feet above sea level.
AMERICAN RIVERS AND LAKES:
Great rivers crisscross North America, linking many of the different physical regions. Many of these rivers
begin in the mountains. They collect runoff water from rains and melting snows and carry it to the oceans.
THE MISSISSIPPI-MISSOURI RIVER SYSTEM The Mississippi and Missouri rivers make up the longest and
most important river system in the United States. The system carries water thousands of miles through the
Interior Plains to the Gulf of Mexico.
IN addition to the two main branches, the Mississippi-Missouri river system includes many tributaries.
A tributary is a stream or smaller river that flows into a larger one. Among the most important tributaries
are the Ohio, Tennessee, Arkansas, and Platte rivers. These and other rivers provide water for the rich
farmlands of the Interior Plains. The Mississippi River also serves as a means of transportation. Today, as in
the past, barges carry freight up and down the river.
OTHER RIVERS The United States includes dozens of other rivers, both large and small. The Colorado River
begins in the Rocky Mountains and flows for about 1,450 miles through Colorado, Utah, Arizona, and Nevada.
It forms the border between California and Arizona as it winds toward the Gulf of California.
Smaller rivers have also been important in American history. The Hudson River, for example, forms
part of the border between New York and New Jersey. Only 306 miles long, it provided a vital link between
New York City and the rich farmlands of upstate New York. In the 1960’s, efforts to clean up pollution of the
Hudson River helped launch the modern environmental movement.
Rivers form political boundaries between the United States and its neighbors. To the south, the Rio
Grand forms part of the border between Texas and Mexico, to the north, the St. Lawrence River separates the
Northeast from Canada.
THE GREAT LAKES The Great Lakes also form part of the border between the United States and Canada.
These five lakes – Superior, Michigan, Huron, Erie, and Ontario – form the largest body of fresh water in the
world. Today, artificial waterways connect the Great Lakes to the St. Lawrence and Mississippi rivers. As a
result, good can be shipped from the Central Plains eastward to the Atlantic Ocean and southward to the Gulf of
Mexico.
CLIMATE AND WEATHER
The condition of the Earth’s atmosphere at a given time and place is its weather. The weather in one
region can influence the weather in another area. It also affects the jobs we do, the leisure activities we enjoy,
and the kinds of homes we build. In history, weather has determined the outcome of battles and even destroyed
civilizations.
The average weather of a place over a period of 20 to 30 years is known as climate. Two main
features that help define an area’s climate are temperature and precipitation, or water that falls in the form of
rain, sleet, hail, or snow. A region may be hot and dry, cold and rainy, or any other combination.
Several factors influence climate. Perhaps the most important is distance from the Equator. Lands near
the Equator are usually hot and wet all year. Closer to the North and South poles, temperatures are cooler.
Altitude, or height of the land above sea level, also affects climate. In general, highlands are cooler than
lowlands. Other factors that affect climate include ocean currents, wind currents, and location of landforms
such as inland mountains, large desert areas, lakes, or forests.
CLIMATES OF THE UNITED STATES
The United States has 10 major climates. Today, as in the past, these climates strongly influence the nation’s
population patterns and economic activities.
MARINE The strip of land from southern Alaska to northern California is sometimes called the Pacific
Northwest. This region has a mild, moist marine climate, with warm summers and cool winters. The Pacific
Northwest has much forest, making it a center of the lumber industry. MEDITERRANEAN Much of California has a Mediterranean climate. Winters are mild and wet. Summers are
hot and dry. Because of dry conditions, farmers and fruit growers must often irrigate the land. This region
produces almost all of the nation’s almond, walnuts, olives, apricots, dates, and figs.
HIGHLANDS In the Cascades, Sierra Nevada, and Rocky Mountains, a highland climate brings cooler
temperatures. Conditions in a highland climate vary according to altitude. For example, Mount Rainier in the
state of Washington, at over 14,000 feet above sea level, is snowcapped all year. The highland climate attracts
vacationers eager to ski in the winter and escape the heat during the summer.
DESERT AND STEPPE Much of the southwestern United States has a desert climate, with hot days and cold
nights. This dry region stretches as far east as the Rockies. The deserts of New Mexico, Nevada, Arizona, and
southeastern California get almost no rainfall. In many places, people irrigate the land so that they can grow
crops.
East of the Rockies, the Great Plains have a steppe climate with limited rainfall, hot summers, and cold
winters. In the 1800’s settlers brought cattle and built a prosperous beef industry in the region.
HUMID CONTINENTAL The Central plains and the northeastern United States have a humid continental
climate. This climate has more precipitation than the steppe. The seasons are marked by mild summers and
cold winters. Tall prairie grasses once covered the Central Plains. Today, American farmers raise much of the
world’s food in this region.
At one time, the humid continental climate supported forests that covered much of the Northeast. While
much of this forestland was cleared to build settlements and grow crops, the region still has a thriving lumber
industry.
TROPICAL AND HUMID SUBTROPICAL Located near the Equator, Southern /Florida and Hawaii have
tropical climates. The hot, humid conditions make these regions good for growing such crops as pineapples and
citrus fruits.
The southeastern United States has a humid subtropical climate. Warm temperatures and regular rainfall
make this region ideal for growing crops such as cotton, soybeans, and peanuts.
TUNDRA AND SUBARCTIC Northern and western coastal regions of Alaska have a tundra climate. It is cold
all year round. The rest of Alaska, as well as northern Canada, has a sub arctic climate with long, cold winters
and short summers.
Relatively few people live in these harsh climates. Farming is limited to a small fertile valley in
southern Alaska. However, the dense forests that cover almost one third of Alaska are ideal for logging and
production of paper pulp.
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