Washington, D. C., formally the District of Columbia

Civil rights and home rule era

The Twenty-third Amendment to the United States Constitution was ratified in 1961, granting the District three votes in the Electoral College for the election of president and vice president, but still no voting representation in Congress.^[34]
After the assassination of civil rights leader Dr. Martin Luther King, Jr., on April 4, 1968, riots broke out in the District, primarily in the U Street, 14th Street, 7th Street, and H Street corridors, centers of black residential and commercial areas. The riots raged for three days until more than 13,600 federal troops stopped the violence. Many stores and other buildings were burned; rebuilding was not completed until the late 1990s.^[35]
In 1973, Congress enacted the District of Columbia Home Rule Act, providing for an elected mayor and 13-member council for the District.^[36] In 1975, Walter Washington became the first elected and first black mayor of the District.^[37]
On September 11, 2001, terrorists hijacked American Airlines Flight 77 and deliberately crashed the plane into the Pentagon in nearby Arlington, Virginia. United Airlines Flight 93, believed to be destined for Washington, D.C., crashed in Pennsylvania when passengers tried to recover control of the plane from hijackers.^[38][39]

Geography

Main article: Geography of Washington, D.C.

The Chesapeake and Ohio Canal passes through the Georgetownneighborhood.
Washington, D.C., is located in the mid-Atlantic region of the U.S. East Coast. Due to the District of Columbia retrocession, the city has a total area of 68.3 square miles (177 km²), of which 61.4 square miles (159 km²) is land and 6.9 square miles (18 km²) (10.16%) is water.^[40] The District is bordered by Montgomery County, Maryland, to the northwest; Prince George's County, Maryland, to the east; and Arlington and Alexandria, Virginia, to the south and west.
The Potomac River forms the District's border with Virginia and has two major tributaries: the Anacostia River and Rock Creek.^[41]Tiber Creek, a natural watercourse that once passed through the National Mall, was fully enclosed underground during the 1870s.^[42] The creek also formed a portion of the now-filled Washington City Canal, which allowed passage through the city to the Anacostia River from 1815 until the 1850s.^[43] The Chesapeake and Ohio Canal starts in Georgetown and was used during the 19th century to bypass the Great Falls of the Potomac River, located upstream (northwest) of Washington at the Atlantic Seaboard fall line.^[44]
The highest natural elevation in the District is 409 feet (125 m) above sea level at Fort Reno Park in upper northwest Washington.^[45]The lowest point is sea level at the Potomac River.^[46] The geographic center of Washington is near the intersection of 4th and L Streets NW.^[47] Contrary to the urban legend, Washington was not built on a reclaimed swamp, but wetlands did cover areas along the water.^[48][49]
The District has 7,464 acres (30.21 km²) of parkland, about 19% of the city's total area and the second-highest percentage among high-density U.S. cities.^[50] TheNational Park Service manages most of the 9,122 acres (36.92 km²) of city land owned by the U.S. government.^[51] Rock Creek Park is a 1,754-acre (7.10 km²) urban forest in Northwest Washington, which extends 9.3 miles (15.0 km) through a stream valley that bisects the city. Established in 1890, it is the country's fourth-oldest national park and is home to a variety of plant and animal species including raccoon, deer, owls, and coyotes.^[52] Other National Park Service properties include the C&O Canal National Historical Park, the National Mall and Memorial Parks, Theodore Roosevelt Island, Columbia Island, Fort Dupont Park, Meridian Hill Park, Kenilworth Park and Aquatic Gardens, and Anacostia Park.^[53] The D.C. Department of Parks and Recreation maintains the city's 900 acres (3.6 km²) of athletic fields and playgrounds, 40 swimming pools, and 68 recreation centers.^[54] The U.S. Department of Agriculture operates the 446-acre (1.80 km²) U.S. National Arboretum in Northeast Washington.^[55]