History: Black And White City Photography, United States

In the 19th century, the United States acquired land from France, Spain, the United Kingdom, Mexico, and Russia, and annexed the Republic of Texas and the Republic of Hawaii. Disputes between the agrarian South and industrial North over states' rights and the expansion of the institution of slavery provoked the American Civil War of the 1860s. The North's victory prevented a permanent split of the country and led to the end of legal slavery in the United States. By the 1870s, the national economy was the world's largest. The Spanish–American War and World War I confirmed the country's status as a military power. It emerged from World War II as the first country with nuclear weapons and a permanent member of the United Nations Security Council. The end of the Cold War and the dissolution of the Soviet Union left the United States as the sole superpower. The country accounts for 43% of global military spending and is a leading economic, political, and cultural force in the world.
Etymology
In 1507, German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere "America" after Italian explorer and cartographer Amerigo Vespucci. The former British colonies first used the country's modern name in the Declaration of Independence, the "unanimous Declaration of the thirteen united States of America" adopted by the "Representatives of the united States of America" on July 4, 1776. On November 15, 1777, the Second Continental Congress adopted the Articles of Confederation, which states, "The Stile of this Confederacy shall be 'The United States of America.'" The Franco-American treaties of 1778 used "United States of North America", but from July 11, 1778, "United States of America" was used on the country's bills of exchange, and it has been the official name ever since.