Washington is located in the humid subtropical climate zone, exhibiting four distinct seasons. Its climate is typical of Mid-Atlantic U.S. areas removed from bodies of water. The District is located in plant hardiness zone 8a near downtown, and zone 7b elsewhere in the city, indicating a temperate climate.

Dialectically, the Washington, D.C., area is extremely heterogeneous. In 2000, 83.2% of all District of Columbia residents five years of age or older spoke only English at home, down from 87% in 1990.

The United States dollar, denoted by USD or the symbol $, is the official currency used in the United States. Commonly referred to as the "American dollar," the currency is divided into 100 cents (symbol ¢).

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The city gained almost 30,000 people since the last census, and more than a third are thought to have moved into the District in the past two years alone, amid a brutal recession. It was the biggest spike since the end of World War II, when the city had 802,000 people

Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States, founded on July 16, 1790.