The United States of America is a large country in North America, often referred to as the "USA," the "U.S.," the "United States," "America," or simply "the States". It has a land area of about 9.6 million sq km (about half the size of Russia and about the same size as China). It also boasts the world's third largest population after China and India, with over 300 million people. It includes both densely-populated cities with sprawling suburbs, and vast, uninhabited and naturally beautiful areas. With its history of mass immigration dating from the 17th century, it is a "melting pot" of cultures from around the world.
Geography and environment
The coastal plain of the Atlantic seaboard gives way further inland to deciduous forests and the rolling hills of the Piedmont. The Appalachian Mountains divide the eastern seaboard from the Great Lakes and the grasslands of the Midwest. The Mississippi–Missouri River, the world's fourth longest river system, runs mainly north–south through the heart of the country. The flat, fertile prairie of the Great Plains stretches to the west, interrupted by a highland region in the southeast. The Rocky Mountains, at the western edge of the Great Plains, extend north to south across the country, reaching altitudes higher than 14,000 feet (4,300 m) in Colorado. Farther west are the rocky Great Basin and deserts such as the Mojave. The Sierra Nevada and Cascade mountain ranges run close to the Pacific coast. At 20,320 feet (6,194 m), Alaska's Mount McKinley is the tallest peak in the country and in North America. Active volcanoes are common throughout Alaska's Alexander and Aleutian Islands, and Hawaii consists of volcanic islands.
The overall climate is temperate, with notable exceptions. Alaska has Arctic tundra, while Hawaii and South Florida are tropical. The Great Plains are dry, flat and grassy, turning into arid desert in the far West and Mediterranean along the California coast.
Washington, D.C., the capital of the United States and the seat of its three branches of government, has a collection of free, public museums unparalleled in size and scope throughout the history of mankind, and the lion's share of the nation's most treasured monuments and memorials.
The United States is made up of many diverse ethnic groups and the culture varies greatly across the vast area of the country and even within cities - a city like New York will have dozens, if not hundreds, of different ethnicities represented within a neighborhood. Despite this difference, there exists a strong sense of national identity and certain predominant cultural traits. Generally, Americans tend to believe strongly in personal responsibility and that an individual determines his or her own success or failure, but it is important to note that there are many exceptions and that a nation as diverse as the United States has literally thousands of distinct cultural traditions.