Washington, D.C., formally the District of Columbia and commonly referred to as Washington. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution. The federal district is therefore not a part of any U.S. state. Washington, D.C., had a resident population of 601,723 in 2010, the 26th most populous city in the USA.
Washington is located in the humid subtropical climate zone and exhibits four distinct seasons. Spring and fall are warm, while winter is cool with annual snowfall averaging 37 cm. Winter temperatures average around 3.3 °C from mid-December to mid-February.