Its the capital of the United States. On July 16, 1790,the United States Congress approved the creation of afederal district to become the national capital aspermitted by the U.S. Constitution. The District istherefore not a part of any U.S. state. It was formedfrom land along the Potomac River donated by thestates of Maryland and Virginia; however, the Virginiaportion was returned by Congress in 1846.
It is estimated that the Districts population was617,996 on July 1, 2011, a 2.7% increase since the2010 United States Census. The city was the24th most populous place in the United States in 2010.According to data from 2009, commuters from thesuburbs increase the Districts daytime population toover one million people.
Spring and fall are warm, while winter is cool withannual snowfall averaging 14.7 inches (37 cm). Wintertemperatures average around 38 °F (3.3 °C) from mid-December to mid-February. Summers are hot andhumid with a July daily average of 79.2 °F (26.2 °C)and average daily relative humidity around 66%, whichcan cause medium to moderate personal discomfort.