The United States (full name, United States of America) covers an area of approximately 9.8 million sq km. Its terrain consists of a vast central plain with mountains in the west, hills and low mountains in the east, rugged mountains and broad river valleys in Alaska, and rugged, volcanic topography in Hawaii. The United States borders Canada and Mexico, and has 19,924 km of coastline. The country is divided into 50 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming) and one district (District of Columbia). Washington DC is the capital, with a time difference of 5 hours behind that of GMT (though the 50 United States cover six time zones). The currency is the US dollar, and exports include computers, electrical machinery, vehicles, chemical products, food, live animals, military equipment and aircraft. The population of approximately 307,200,000 people comprises an ethnic makeup that is 79.96% white and 12.85% black (about 15% of the population is Hispanic, though this can refer to a number of ethnic origins). The primary language is English, and the predominant religion is Christianity.