USA

The United States is a country in North America made up of 50 states, plus the federal district of Washington, D.C. Its territory covers about 9.8 million km², making it one of the world's largest countries by area. Most of the country lies between Canada to the north and Mexico to the south, with coastlines on the Atlantic Ocean, the Pacific Ocean and the Gulf of Mexico.

Alaska, separated from the other states by Canada, lies in the far northwest of North America, while Hawaii is an island state in the central Pacific. This wide territory includes plains, forests, deserts, mountains and long coastlines, creating strong regional differences in landscapes and climate. Several major mountain systems cross the country.

The Rocky Mountains extend through the west, while the Appalachian Mountains occupy much of the east. Between them lie broad plains and river basins, including the Mississippi-Missouri system, one of the largest drainage networks in North America. The highest point in the United States is Denali, in Alaska, at 6,190 m above sea level.

Hawaii is largely volcanic and contains active volcanoes, showing that the country's landscapes are shaped by different geological processes. Because the territory stretches from the Arctic environment of northern Alaska to the tropical climate of Hawaii, the United States contains a remarkable range of climates and ecosystems.