The Coastal Plains
A lowland area sweeps from Massachusetts to Texas along the coasts of the Atlantic Ocean and the Gulf of Mexico. This coastal plain, which extends for more than3,219 kilometers is divided into two parts — the Atlantic Coastal Plain and the Gulf Coastal Plain. The Atlantic Plain follows the coastline of the Atlantic Ocean south from Cape Cod in Massachusetts to the Florida Peninsula. The coastline is irregular. Many natural harbours have been created. Some of the more important ones are Massachusetts Bay, New York Bay, Delaware Bay, Chesapeake Bay, and Long Island Sound.
The Gulf Plain is a much wider band of flat land and gently rolling hills. It varies in width from 241 kilometers to about 966 kilometers. At one point, the plain extends far inland to where the Ohio River flows into the Mississippi River. The Mississippi, the longest river in North America, empties into the Gulf of Mexico in Southern Louisiana. There it has made a huge delta. This part of the Gulf Coastal Plain is made up of marshes and bayous — a word used to describe the many small, marshy creeks and rivers that flow through the delta area.
The Appalachian Highlands
Just west of the Atlantic Coastal Plain is the Appalachian Highlands. This region takes its name from the Appalachian Mountains. The highlands stretch about 1,931 kilometers in the United States from northern Maine to central Alabama. They lie in a northeast to southwest direction. In the highlands is the highest peak in the eastern United States — Mount Mitchell in western North Carolina. It rises 2,037 meters above sea level.
The eastern edge of the highlands is known as the Piedmont. This low plateau varies in altitude from 152 to 305 meters above sea level. West of the Piedmont are the Appalachian Mountains. They are nearly parallel with the Atlantic coastline.
The Interior Plains
A huge "plain region" covers the middle of the United States between the Appalachian Mountains and the Rockies. The region is divided into Central Plains the Great Plains. The Central Plains include lowland parts of central and western Kentucky and Tennessee, the Great Lakes area, and the upper Mississippi and lower Ohio and Missouri river basins. West of the river basins is the area of the Great Plains. Many long rivers flow eastward from the Great Plains, emptying into the Mississippi.
The Interior Highlands
Two separate highlands regions rise above the plains in the central United States. These are the Superior Highlands and the Ozark Plateau.
Located around Lake Superior, in the northern parts of Minnesota, Wisconsin, and Michigan, the Superior Highlands are actually a part of the Canadian Shield. Coniferous forests cover rocky plateaus. There are many lakes among the hills. The Ozark Plateau is located between the Missouri and Arkansas rivers west of the Mississippi River. The land is gently rolling in places with some rugged mountains in other places.
The Rocky Mountains
West of the Great Plains is the Rocky Mountain region. The Rocky Mountains extend from Canada south to New Mexico and Western Texas. The region occupies an area over 1,600 kilometers long, it varies in width between 200 to 600 kilometers.
The Rockies stretch from north to south. The Rocky Mountains are much more rugged and much higher than the Appalachians. Many peaks are over 3,658 meters high. Plants are greatly affected by altitude. Mountain tops not covered by snow are capped by tundra grasses and mosses.
Intermontane Plateaus
West of the Rocky Mountains lies an area of intermontane plateaus and basins. The term intermontane means "between mountains". The region lies between the Rocky Mountains and mountain ranges along the Pacific coast.
The intermontane area is long and broad, stretching from Washington to the border with Mexico. The mountains block rain, and as a result, the lowland basins are dry. Some of the most impressive landscapes in the country are found in the region. The best known is the Grand Canyon.
