The United States is a country located in North America and is comprised of 50 states, five self-governing territories, and several protectorates. Its capital is Washington DC, a federal territory located in the eastern part of the country. It shares borders with Canada and Mexico. Many indigenous peoples populated the land. European colonization began in the sixteenth century, and the British established 13 colonies along the east coast. Spain and France also controlled larger areas in the south and west. The British colonies earned independence following the American Revolution, which ended in 1783. The American South long depended on slave labor for its economy, which was a major factor prompting the American Civil War from 1861-1865, which ended with the abolition of slavery, though intense racial tension and injustice continued for many decades. The United States emerged as a global superpower in the twentieth century and was the first to have and use nuclear weapons. Major American authors include Nathaniel Hawthorne, Herman Melville, Mark Twain, Kate Chopin, Edith Wharton, Walt Whitman, Harriet Beecher Stowe, Eudora Welty, and Ernest Hemingway.