Map - Aurora County, South Dakota (Aurora County)

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The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C., and its most populous city and principal financial center is New York City.

Indigenous peoples have inhabited the Americas for thousands of years. Beginning in 1607, British colonization led to the establishment of the Thirteen Colonies in what is now the Eastern United States. They quarreled with the British Crown over taxation and political representation, leading to the American Revolution and proceeding Revolutionary War. The United States declared independence on July 4, 1776, becoming the first nation-state founded on Enlightenment principles of unalienable natural rights, consent of the governed, and liberal democracy. The country began expanding across North America, spanning the continent by 1848. Sectional division surrounding slavery in the Southern United States led to the secession of the Confederate States of America, which fought the remaining states of the Union during the American Civil War (1861–1865). With the Union's victory and preservation, slavery was abolished nationally by the Thirteenth Amendment.