Geography of Washington, D.C.


, in the United States, is located at . According to the United States Census Bureau, the city has a geographical area of, of which is land, and the remaining of which is water.
Washington is surrounded by the states of Virginia and Maryland ; it interrupts those states' common border, which is the south shore of the Potomac River both upstream and downstream from the District. The portion of the Potomac River that passes Washington is virtually entirely within the District's border, as the District extends to the south bank. The city contains the historic "federal city", the territory of which was formerly part of those two adjacent states before they respectively ceded it for the national capital. The land ceded from Virginia was returned by Congress in 1847, so what remains of the modern District was all once part of Maryland.

Topography and geology

The topography of the District of Columbia is highly similar to the physical geography of much of Central and DC Metro Maryland. The District has three major natural flowing bodies of water: the Potomac River and two tributaries, the Anacostia River and Rock Creek. The confluence of the Potomac and Anacostia forms the historic peninsula known as Arsenal Point. The District also includes the Washington Channel, which flows into the junction of the Anacostia and Potomac rivers. There are also three man-made reservoirs: Dalecarlia Reservoir, which crosses over the northwest border of the District from Maryland, McMillan Reservoir near Howard University, and Georgetown Reservoir upstream of Georgetown. A fourth, minor reservoir is at Fort Reno in Tenleytown.
Washington, D.C. is situated in a topographic bowl. The bottom of the bowl, where the White House and Capitol are located, is in the floodplain of the junction of the Anacostia and Potomac Rivers. Extending out from the floodplain is a series of rising river terraces. These high ridges nearly surround the city. The highest of these terraces is at 200 feet above sea level and is fronted by an escarpment which is very prominent along the east side of the Anacostia River. Steep sided ravines and small streams cut through the upper terrace east of the Anacostia River at frequent intervals. Examples of these stream valleys can be found at Forts Dupont and Stanton.
The City of Washington is located on the fall line—the border of two considerably different geological terrains or provinces; the hard rock of the Piedmont Plateau to the north and west, and the soft sediments of the Atlantic Coastal Plain to the east. The Piedmont Plateau is located north and west of the city. This area is characterized by deeply cut valleys and prominent ridges.
The highest point in the District of Columbia is 410 feet above sea level at Reno Reservoir in Tenleytown. The lowest point is sea level, which occurs along all of the Anacostia shore and all of the Potomac shore except the uppermost mile. The sea level Tidal Basin rose eleven feet during Hurricane Isabel on September 18, 2003. The geographic center of the District of Columbia is near 4th Street NW, L Street NW, and New York Avenue NW, not, as is sometimes stated, under the Capitol dome.
Other prominent geographical features of Washington, D.C., include Theodore Roosevelt Island, Columbia Island, the Three Sisters, and Hains Point.
Some areas, especially around the National Mall and parts of Foggy Bottom, were marshes or parts of the river that have been filled in.

Natural history

During the 18th century, significant portions of the region were forested, with species including rabbits, turkey, pheasants, woodcocks, turtles, and quail, as well as numerous bird species including mockingbirds, bluebirds, hummingbirds, and orioles. Other indigenous species include black snake, garter snake, rattlesnake, copperhead, bullfrog and other types of frogs, ground squirrels, flying squirrels, skunks, opossums, raccoons, foxes, beavers, deer, wolves, and bears. Snipes and various types of ducks inhabited swampy areas, as well as soruses.
Native tree species include willow, birch, cedar, and oak. Other plant species found along the Potomac during the early 19th century include yellow jessamine, prickly pear cactus, white horehound, sweet fennel, wild cherries, and wild strawberries. The large percentage of parkland contributes to a high urban tree canopy coverage of 35%.
In 1965, President Lyndon Johnson called the Potomac River a "national disgrace" and used the river to illustrate the need for the Clean Water Restoration Act of 1966. The river is now home to a vibrant warm-water fishery and naturally reproducing bald eagles have returned to its banks. Despite its intensely urbanized landscape, the District of Columbia is a center for research on urban wildlife management, invasive species management, urban stream restoration, and the aquatic ecology of urban streams. The National Park Service's Center For Urban Ecology is a regional source of expertise and applied science for the region.

Earthquakes

Earthquake activity in the District of Columbia is low. No earthquakes have been centered within the District, nor are there any faults. However, it has felt earthquakes centered in Virginia, Maryland and other surrounding states and also large earthquakes in Canada and New England.
The District felt the 1811–1812 New Madrid earthquakes, and according to old records, residents were "badly frightened". In March 1828, President John Quincy Adams felt a "violent" earthquake in the White House and wrote it in his journal. The 1886 Charleston earthquake was felt in DC. The strongest earthquake in Virginia happened in 1897 and was felt in the District. An earthquake in 1925 in Canada, estimated about magnitude 7, was felt over an area of 2 million square miles. Another 6.2 earthquake in 1935 caused damage in New York and shook residents from Maine to Wisconsin.
The 2011 Virginia earthquake was felt in Washington and caused damage to landmarks and monuments such as the Washington Monument and the Washington National Cathedral.

Climate

Washington, D.C. is located in the humid subtropical climate zone, exhibiting four distinct seasons. Its climate is typical of the South. The District is located in USDA plant hardiness zone 8a near downtown, and zone 7b elsewhere in the city, indicating a temperate climate. As implied in the previous sentence, the downtown area exhibits an urban heat island build-up that can especially exacerbate the sultriness of summer nights.
The highest recorded temperature was on July 20, 1930, and August 6, 1918, while the lowest recorded temperature was on February 11, 1899, right before the Great Blizzard of 1899. The extreme low daily high temperature was, occurring one day before the all-time minimum, while the extreme high daily low temperature was on July 23–24, 2011 and July 16, 1983. Monthly mean temperatures have ranged from in January 1918 to in July 2011, while the corresponding range for the annual mean is in 1904 to in 2012.

Monthly statistics

City plan

Washington, D.C., was created to serve as the national capital from its inception. The Residence Act of 1790 required that the capital's territory would be located along the Potomac River within an area that Maryland and Virginia would cede to the federal government, but permitted the nation's first president, George Washington, to select the territory's precise location. President Washington then chose for the territory a square whose sides were in length and whose corners were directly north, east, south and west of its center. The area of the square contained the existing towns of Georgetown and Alexandria, as well as two small villages, Hamburgh in the Foggy Bottom area and Carrollsburg near the confluence of the Potomac and Anacostia rivers.
The Residence Act had granted the president the authority to locate the federal capital's territory only as far south and east as the mouth of the Anacostia River in Maryland. However, President Washington wanted to expand the territory's area southward so that its boundaries could encompass the town of Alexandria. In 1791, Congress amended the Residence Act to approve President Washington's selected site, which included the portion of the territory that Virginia would cede.
The location of the capital had many natural advantages: the Potomac was navigable up to the territory, allowing for boat traffic; the established ports at Alexandria and Georgetown could provide an important economic base for a major city; and the territory's inland location was close to the Northwest Territory. During 1791–1792, Andrew Ellicott and several assistants, including Benjamin Banneker, surveyed the boundary between the federal territory and the states of Virginia and Maryland, placing marker stones at every mile point. Many of the stones are still standing.
A new federal city, named in 1791 as the “City of Washington” in the “Territory of Columbia”, was then laid out in a largely undeveloped area at the center of the 100 square mile federal territory. This city, which Pierre L’Enfant designed, was bounded to the north by Boundary Street at the base of the escarpment of the Atlantic Seaboard Fall Line, to the southeast by the Anacostia River, to the southwest by the Potomac River and to the west by Rock Creek. Although L’Enfant designed the city's original layout in 1791, surveyor Andrew Ellicott revised it in 1792.
The remainder of the territory was designated as Washington County and Alexandria County.

Alexandria

The land from the state of Virginia was eventually returned to the state in 1846, effective 1847. This land in Virginia makes up the modern area of Arlington County and the old part of Alexandria, Virginia, both of which are considered suburbs of Washington. In fact, the Arlington National Cemetery and the Pentagon complex are both located in Arlington but are largely tied to the federal government in Washington. Between 1790 and 1846, Alexandria was referred to as “Alexandria, D.C.”

Georgetown

Georgetown was originally part of Maryland and was the only significant population in the area that would become the District of Columbia. Georgetown became part of the District when the Federal City was first created, but remained an independent city, referred to as "Georgetown, D.C.," until 1871, when it was merged with Washington City and Washington County, completing the process of Washington and the District of Columbia occupying the same geographic borders.

McMillan plan

The monumental core of the city consists of the National Mall and many key federal buildings, monuments, and museums, including the Washington Monument, Lincoln Memorial, and the National Air and Space Museum. Its layout is based on that proposed by the McMillan Commission report in 1901.

Building heights

To preserve the grandeur of the National Mall, the White House, the Capitol, and various other key locations, the entire city is subject to strict building height limits. This limitation was placed in effect just prior to the 20th century when government officials realized that structural steel "skyscrapers" could overwhelm the city. In 1899, Congress enacted a height limit for the District prohibiting private buildings from rising more than 130 feet. Contrary to popular belief, no law has ever restricted buildings to the height of the United States Capitol or Washington Monument.
A revised height law in 1910 did away with that fixed maximum. The newer legislation, still in effect today, states that no new building may be more than 20 feet taller than the width of the street in front of it. The current law is codified as D.C. CODE ANN. § 6-601.05. Thus, Washington has a relatively modest skyline in comparison to the majority of American cities. However, the District is ringed by high-rise buildings in many nearby suburbs like Arlington, Silver Spring, and Bethesda.

Neighborhoods

The District of Columbia is divided into eight wards and 37 Advisory Neighborhood Commissions within these wards. The total number of named neighborhoods is 127. The ANCs serve to advise the D.C. Council on neighborhood matters. The Council is required by law to give their opinions "great weight," though what that means is up to the Council to decide.
Since 2000 the demographics of many neighborhoods have changed markedly.

Adjacent communities

The District of Columbia is bordered by various cities, towns, villages, and unincorporated CDPs in the states of Maryland and Virginia. Following is a list of those adjacent communities.
  • Bethesda, Maryland
  • Brookmont, Maryland
  • Capitol Heights, Maryland
  • Chevy Chase, Maryland
  • Chevy Chase Village, Maryland
  • Chillum, Maryland
  • Colmar Manor, Maryland
  • Coral Hills, Maryland
  • Cottage City, Maryland
  • Fairmount Heights, Maryland
  • Glassmanor, Maryland
  • Hillcrest Heights, Maryland
  • Mount Rainier, Maryland
  • Seat Pleasant, Maryland
  • Silver Hill, Maryland
  • Silver Spring, Maryland
  • Suitland, Maryland
  • Takoma Park, Maryland
  • Alexandria, Virginia
  • Arlington, Virginia
  • McLean, Virginia
In addition to the above named places, there are other small unincorporated parts of Prince George's County, Maryland, which also border the District.