United States: Physical Geography

The conterminous United States may be divided into seven broad physiographic divisions: from east to west, the Atlantic–Gulf Coastal Plain; the Appalachian Highlands; the Interior Plains; the Interior Highlands; the Rocky Mountain System; the Intermontane Region; and the Pacific Mountain System. An eighth division, the Laurentian Uplands, a part of the Canadian Shield, dips into the United States from Canada in the Great Lakes region. It is an area of little local relief, with an irregular drainage system and many lakes, as well as some of the oldest exposed rocks in the United States.

The terrain of the N United States was formed by the great continental ice sheets that covered N North America during the late Cenozoic Era. The southern edge of the ice sheet is roughly traced by a line of terminal moraines extending west from E Long Island and then along the course of the Ohio and Missouri rivers to the Rocky Mts.; land north of this line is covered by glacial material. Alaska and the mountains of NW United States had extensive mountain glaciers and were heavily eroded. Large glacial lakes (see Lake Bonneville under Bonneville Salt Flats; Lahontan, Lake) occupied sections of the Basin and Range province; the Great Salt Lake and the other lakes of this region are remnants of the glacial lakes.

Sections in this article:

• Introduction
• Related Articles
• The George W. Bush Presidency, 9/11, and Iraq
• Bush, Clinton, and Bush
• The Reagan Years
• Internationalism and the End of the Cold WarFord and Carter
• The Nixon Years
• The Great Society, the Vietnam War, and Watergate and the Vietnam War
• The United States in a Divided World
• World War II
• From Prosperity to Depression
• World War I
• Expansionists and Progressives
• The Late Nineteenth Century
• Slavery, Civil War, and Reconstruction
• Jackson to the Mexican War
• Madison, Monroe, and Adams
• Washington, Adams, and Jefferson
• The States in Union
• Colonial America
• European Exploration and Settlement
• Government
• Economy
• Religion and Education
• People
• Climate
• Major Rivers and Lakes
• The Pacific Coast, Alaska, and Hawaii
• The Western Mountains and Great Basin
• The Plains and Highlands of the Interior
• The East and the Gulf Coast
• Physical Geography
• Political Geography
• Geographical Studies

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2024, Columbia University Press. All rights reserved.

See more Encyclopedia articles on: U.S. Political Geography