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Section 1, continued

/ Main Ideas
1. Major physical features of the United States include mountains, rivers, and plains.
2. The climate of the United States is wetter in the East and South and drier in the West.
3. The United States is rich in natural resources such as farmland, oil, forests, and minerals.
Key Terms and Places
Appalachian Mountains the main mountain range in the East
Great Lakes the largest group of freshwater lakes in the world
Mississippi River North America’s longest river
tributary a stream or river that flows into a larger stream or river
Rocky Mountains an enormous mountain range in the West
continental divide an area of high ground that divides the flow of rivers towards opposite ends of a continent

Section Summary

PHYSICAL FEATURES

The United States is one of the largest countries in the world. On the eastern coast of the United States, the land is flat and close to sea level. This area is called the Atlantic Coastal Plain. Moving west, the land rises to a region called the Piedmont. The land rises higher in the Appalachian Mountains, the main mountain range in the East. The highest peak in the Appalachians is about 6,700 feet (2,040m).

West of the Appalachian Mountains are the Interior Plains. The plains are filled with rolling hills, lakes, and rivers. The main physical features of the Interior Plains are the Great Lakes. The Great Lakes are the largest freshwater lake system in the world. They are also an important waterway for trade between the United States and Canada.

The Mississippi River lies west of the Great Lakes. It is the longest river in North America. Tributaries of the Mississippi River deposit rich silt that produces fertile farmlands. These farmlands cover most of the Interior Plains.

West of the Mississippi River lie the Great Plains. These are vast areas of grasslands. Further west, the land begins to rise, eventually leading to the Rocky Mountains. Many of these mountains reach higher than 14,000 feet (4,267m). Along the crest of the Rocky Mountains is a ridge that divides North America’s rivers. This is called a continental divide. Rivers east of the divide mostly flow eastward, and most rivers west of the divide flow westward.

Farther west, mountain ranges include the Cascade Range and the Sierra Nevada. Mountains also stretch north along the Pacific coast. Mount McKinley in Alaska is the highest mountain in North America.

CLIMATE

The eastern United States is divided into three climate regions. The Northeast has a humid continental climate. To the south, the climate is humid subtropical. Farthest south, in the tip of southern Florida, the climate is tropical savanna.

The climate in the Interior Plains varies. It is hot and dry in the Great Plains. But in most of the Midwest, the climate is humid continental. In the West, climates are mostly dry. Alaska has subarctic and tundra climates, while Hawaii is tropical.

NATURAL RESOURCES

Our lives are affected by natural resources every day.
Much of our paper, food, gas, and electricity come from natural resources in the United States.

CHALLENGE ACTIVITY

Critical Thinking: Drawing Inferences Write three paragraphs describing what makes the physical geography of the United States so diverse.

Appalachian Moutains / continental divide / Great Plains
Rocky Mountains / Great Lakes / Mississippi River
tributary

DIRECTIONS Read each sentence and fill in the blank with the word in the word pair that best completes the sentence.

1. Grasslands cover most of the ______, making the region a good place to grow wheat and other grains. (Rocky Mountains/Great Plains)

2. The Missouri and Ohio Rivers are two major tributaries of the ______. (Great Lakes/Mississippi River)

3. The ______separate(s) the flow of North America’s rivers, sending some water east into the Mississippi River and some water west into the Pacific Ocean. (tributary/continental divide)

DIRECTIONS On the line provided before each statement, write T if a statement is true and F if a statement is false. If the statement is false, write the term from the word bank that would make the statement correct on the line after each sentence.

4. The Rocky Mountains are the main mountain range in the East.

5. The Mississippi River is (are) an important waterway for trade between the United States and Canada.

DIRECTIONS Write three words or phrases that describe the term.

6. tributary

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53 Guided Reading Workbook