The United States is the world's third largest country by land area, after Russia and Canada. It is bounded by the North Atlantic Ocean to the east, the North Pacific Ocean to the west, Mexico and the Gulf of Mexico to the south, and Canada to the north. Alaska also borders Canada, with the Pacific Ocean to its south and the Arctic Ocean to its north. The island state of Hawaii is situated in the Pacific, southwest of the North American mainland.

A satellite composite image of the contiguous U.S. Deciduous vegetation and grasslands prevail in the east, transitioning to prairies, boreal forests, and the Rocky Mountains in the west, and deserts in the southwest. In the northeast, the coasts of the Great Lakes and Atlantic seaboard host much of the country's population.

The U.S. has an extremely varied geography, particularly in the West. The eastern seaboard has a coastal plain which is widest in the south and almost nonexistent in the north. Beyond the coastal plain, the rolling hills of the piedmont region end at the Appalachian Mountains which rise above 6,000 feet (1,830 m) in North Carolina and New Hampshire. From the west slope of the Appalachians, the Midwestern prairie is relatively flat and is the location of the Great Lakes as well as the Mississippi-Missouri River, the world's fourth longest river system. West of the Mississippi River, the prairie slopes uphill and blends into the vast and oftentimes featureless Great Plains. The abrupt rise of the Rocky Mountains at the western edge of the great plains, extends the entire width of the continental U.S., reaching altitudes over 14,000 feet (4,270 m) in Colorado. In the past, the Rocky Mountains had a higher level of volcanic activity; nowadays, the range only has one area of volcanism, Yellowstone National Park in Wyoming, possibly the world's largest volcano. Dozens of high mountain ranges, salt flats such as the Bonneville Salt Flats, and valleys are found in the Great Basin region located west of the Rockies and east of the Sierra Nevadas, which also has deep chasms, including the Snake River. At the southwestern end of the Great Basin, Death Valley lies below sea level and is the lowest point in the Western Hemisphere and is situated near the Mojave Desert. North of the Great Basin and east of the Cascades in the Northwest is the Columbia River Plateau, a large igneous province caused by one of the largest flood basalts ever to appear on Earth, it is marked by dark black rocks. Near the Four Corners region lies the Colorado Plateau, named after the Colorado River, which flows through it. The Plateau is generally high in elevation, has highly eroded sandstone, and is a blood red in some locations with many national parks, such as Arches, Bryce Canyon, Grand Canyon, and Zion. Immediately to the east of the continental Pacific Coast, the Sierra Nevada mountain range has Mount Whitney, the highest peak in the continental U.S. Along the Pacific coast, the Coast Ranges and the volcanic Cascade Range extend across the width of the country. Alaska has numerous mountain ranges, including Mount McKinley (Denali), the highest peak in North America. Numerous volcanoes can be found throughout the Alexander and Aleutian Islands extending south and west of the Alaskan mainland. The Hawaiian islands are tropical, volcanic islands extending over 1,500 miles (2,400 km), and consisting of six larger islands and another dozen smaller ones that are inhabited.