#1

United States - Physical Features

BODIES OF WATER

The United States is made up of 50 states, plus Washington, D.C. The 48 states that touch are called contiguous, meaning they are connected. The United States is bordered by the Pacific Ocean in the west, the Atlantic Ocean in the east, and the Gulf of Mexico in the southeast. Included in the land area of the United States are numerous fresh water lakes and rivers. The rivers are important for transportation and irrigation, or supplying water to dry land. Many of the rivers are navigable, or wide and deep enough to allow the passage of ships.

#2

The Great Lakes

The term Great Lakes refers to a cluster of five huge lakes located in the American Midwest and central Canada. They form the largest group of freshwater lakes in the world. From west to east they are: Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario. Water flows from west to east from one lake to the next and then into the St. Lawrence River. Locks have been built between the lakes and the St. Lawrence River. Water travels 2,340 miles from Lake Superior to the Atlantic Ocean

#3

The Mississippi River System

The “Mighty Mississippi” is one of the longest rivers in North America. From its source in Minnesota, the Mississippi River winds its way southward for 2,350 miles to the Gulf of Mexico. The Missouri River and Ohio River are two of the tributaries that feed into the Mississippi. The U.S. government has built levees along the river.

#4

Western Lakes and Rivers

The United States west of the Mississippi River is much drier than the eastern part of the country. Utah’s Great Salt Lake, the largest salt water lake in the Americas, is located in this region. Two other important lakes in the region are Lake Tahoe and Lake Mead. Lake Mead is a man-made lake formed when Hoover Dam was built on the Colorado River. The Colorado is in the southern part of the region. The Columbia River is in the northern part of the region.

The Continental Divide is located on the high ridge of the Rocky Mountains.

#5

LANDSCAPES AND RESOURCES

Coastal Plains

Coastal plains are found in the United States along the Atlantic and Gulf of Mexico. These areas are excellent locations for harbors and large cities, such as Boston, New York City, Houston, and New Orleans.

The thin rocky soil of the Atlantic coastal plain limits farming. The coastal plain along the Gulf of Mexico is wider and the soils are better. The fertile soil and mild, moist climate make the coastal plain along the Gulf of Mexico a producer of many agricultural products. A wealth of natural resources is hidden below the surface of the coastal plains. They include minerals, such as iron ore, gold, zinc, and fossil fuels, such as coal, oil, and natural gas.

#6

Appalachian Mountains

The Appalachian Mountains run from eastern Canada to Alabama. They are the oldest mountains in North America. The highest peak in the range is Mt. Mitchell in North Carolina.

On the eastern side of the Appalachians there is a fertile, hilly area known as the Piedmont. There is a boundary called the fall line between the Piedmont and the Atlantic coastal plain.

#7

Central Lowlands and Great Plains

The Central Lowlands are west of the Appalachians. There are grassy hills, rolling flatlands, thick forests, and fertile farmlands. The Great Lakes and the Mississippi River are here. Large cities, such as Chicago, Detroit, Cleveland, and St. Louis, are located here.

The Great Plains stretch west of the Mississippi River and gradually rise in

elevation from east to west. Much of this region is prairie, or rolling inland grasslands with fertile soil. This region was once home to millions of bison and Native Americans. Today, farmers grow grains, and ranchers raise cattle. There are reserves of coal, oil, and natural gas. Cities, such as Omaha and Dallas, are important centers of industry and commerce.

#8Rocky Mountains and Plateaus

West of the Great Plains tower the Rocky Mountains. The Rockies are not a single mountain chain, but a cordillera. The Rockies extend from Canada to Mexico. Trees cover the slopes but not above the timberline.

Near the Pacific coast is a series of mountain chains that make up the western part of the cordillera. They are the Sierra Nevada, the Cascade Range, the Coast Ranges, and the Alaska Range. Mount McKinley in the Alaska Range is the highest point in North America.

Between the Rocky Mountains and the Pacific ranges is a stretch of dry basins and plateaus. In the southern part, rivers have worn through rock to create magnificent canyons, or deep valleys with steep sides. The most famous of these is the Grand Canyon of the Colorado River.

#9

In the region west of the Great Plains, there are large reserves of energy resources. Petroleum is found in the Gulf of Mexico, near Louisiana and Texas, and in California and Alaska. Natural gas is found in the same areas.

A growing source of energy coming from this region is ethanol. In the United States, ethanol is made from corn and blended with gasoline. The United States is one of the world’s leading producers of ethanol.

#10

Hydroelectric power is an important source of energy in the western United States. Dams along the Columbia and Colorado rivers supply this power. Wind power is a growing source of energy here. Solar power is also becoming important.

The West is an important source of gold, silver, copper, zinc, and lead. Timber is an important resource. This area is home to many national parks.

#11

Climates

Climate Zones

Coastal areas tend to have mild climates. The Great Plains benefit from moisture-bearing winds from the Gulf of Mexico and from the Arctic that result in hot, humid summers and cold, snowy winters. Enough precipitation falls to support grasses and grains, but droughts, or long periods without rainfall, sometimes affect the area.

The inland West has a desert climate of hot summers and mild winters. Because the mountains block the humid ocean winds of the Pacific, this area gets little rainfall.

#12

On the eastern side of the Rockies, temperatures get hot in the summer and cold in the winter. Chinooks sometimes blow over the area.

Alaska has a generally cool to cold climate. Southern California has a Mediterranean climate of warm, dry summers and mild, wet winters. Hawaii, in the middle of the Pacific, has a tropical rain forest climate with steady ocean breezes keeping temperatures mild.Alaska

California

Hawaii

#13Natural Hazards

The Great Plains experiences more tornadoes than any other parts of the country. From northern Texas through Oklahoma, Kansas, part of Colorado, Nebraska, Iowa, and small parts of South Dakota and Minnesota is “Tornado Alley” because of the likelihood of tornadoes.

Coastal areas along the Gulf Coast and the East Coast are vulnerable to hurricanes. Hurricanes can develop in the Pacific Ocean but usually move away from the Pacific Coast of the United States. On average, about two hurricanes strike the U.S. in the Gulf of Mexico and the Atlantic each year.

Earthquakes and volcanoes affect the Pacific Coast as well as Alaska and Hawaii. A major fault system called the San Andreas Fault cuts through western California. Wildfires and mud slides can also strike this region.