Washington D.C. (D.C. means District of Columbia), the capital of the USA, is situated on the Potomac River about 90 miles inland from the Atlantic Ocean. (Columbia was a popular name given to the United States in the 18th century in honour of Christopher Columbus.) The Potomac River is too shallow to allow large cargo-carrying ships to enter the city, so Washigton never developed into a major port. Along the Potomac River, there are the most important buildings in the USA – the White House (residence of the American President), the Capitol (the seat of the Congress, having two parts: the House of Representatives and the Senate) and the Pentagon (the headquarters of US military force).
Washington is the U.S. legislative, administrative and judicial center.
Washington has a population of about 700,000 (metropolitan area almost 4 millions). The racial mix of the city is roughly 70 per cent black and 30 per cent white.
There are no factories and industry in Washington and that is why the city looks so clean and nice. Because a large part of the population is employed by the Federal Government, Washington is also called a white-collar city.