Demographics

The land area of the contiguous United States is 2,959,064 square miles (7,663,941 km²). Alaska, separated from the contiguous United States by Canada, is the largest state at 663,268 square miles (1,717,856 km²). Hawaii, occupying an archipelago in the central Pacific, southwest of North America, is 10,931 square miles (28,311 km²) in area.
The United States is the world's third or fourth largest nation by total area (land and water), ranking behind Russia and Canada and just above or belowChina. The ranking varies depending on how two territories disputed by China and India are counted and how the total size of the United States is measured: calculations range from 3,676,486 square miles (9,522,055 km²) to 3,717,813 square miles (9,629,091 km²)

to 3,794,101 square miles (9,826,676 km²) Measured by only land area, the United States is third in size behind Russia and China, just ahead of Canada.

The coastal plain of the Atlantic seaboard gives way further inland to deciduous forests and the rolling hills of the Piedmont. The Appalachian Mountainsdivide 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 U.S. Census Bureau estimates the country's population now to be 317,785,000,^] including an approximate 11.2 million illegal immigrants The U.S. population almost quadrupled during the 20th century, from about 76 million in 1900.^] The third most populous nation in the world, after China and India, the United States is the only major industrialized nation in which large population increases are projected.

With a birth rate of 13 per 1,000, 35% below the world average, its population growth rate is positive at 0.9%, significantly higher than those of many developed nations. In fiscal year 2012, over one million immigrants (most of whom entered through family reunification) were granted legal residence. Mexico has been the leading source of new residents since the 1965 Immigration Act. China, India, and the Philippines have been in the top four sending countries every year. Nine million Americans identify themselves as homosexual, bisexual, or transgender.^] A 2010 survey found that seven percent of men and eight percent of women identified themselves as gay, lesbian, or bisexual.

The United States has a very diverse population—31 ancestry groups have more than one million members. White Americans are the largest racial group; German Americans, Irish Americans, and English Americans constitute three of the country's four largest ancestry groups. Black Americans are the nation's largest racial minority and third largest ancestry group. Asian Americans are the country's second largest racial minority; the three largest Asian American ethnic groups are Chinese Americans, Filipino Americans, and Indian Americans.

In 2010, the U.S. population included an estimated 5.2 million people with some American Indian or Alaska Nativeancestry (2.9 million exclusively of such ancestry) and 1.2 million with some native Hawaiian or Pacific island ancestry (0.5 million exclusively). The census counted more than 19 million people of "Some Other Race" who were "unable to identify with any" of its five official race categories in 2010.