The architecture of Washington varies greatly. Six of the top 10 buildings in the American Institute of Architects' 2007 ranking of "America's Favorite Architecture" are located in the District of Columbia: the White House; the Washington National Cathedral; the Thomas Jefferson Memorial; the United States Capitol; the Lincoln Memorial; and the Vietnam Veterans Memorial. The neoclassical, Georgian, gothic, and modern architectural styles are all reflected among those six structures and many other prominent edifices in Washington. Notable exceptions include buildings constructed in the French Second Empire style such as the Eisenhower Executive Office Building.
Outside downtown Washington, architectural styles are even more varied. Historic buildings are designed primarily in the Queen Anne, Châteauesque, Richardsonian Romanesque, Georgian revival, Beaux-Arts, and a variety of Victorian styles. Rowhouses are especially prominent in areas developed after the Civil War and typically follow Federalist and late Victorian designs.
Since Georgetown was established before the city of Washington, the neighborhood features the District's oldest architecture. Georgetown's Old Stone House was built in 1765, making it the oldest-standing original building in the city. The majority of current homes in the neighborhood, however, were not built until the 1870s and reflect late Victorian designs of the period. Founded in 1789, Georgetown University is more distinct from the neighborhood and features a mix of Romanesque and Gothic Revival architecture. The Ronald Reagan Building is the largest building in the District with a total area of approximately 3.1 million square feet (288,000 m2).
The U.S. Census Bureau estimates that the District's population was 617,996 on July 1, 2011, a 2.7% increase since the 2010 United States Census. The increase continues a growth trend since 2000, following a half-century of population decline. The city was the 24th most populous place in the United States as of 2010. According to data from 2009, commuters from the suburbs increase the District's daytime population to over one million people. If the District were a state it would rank 50th in population, ahead of Wyoming.
The Washington Metropolitan Area, which includes the District and surrounding suburbs, is the seventh-largest metropolitan area in the United States with approximately 5.6 million residents as of the 2010 Census. When the Washington area is included with Baltimore and its suburbs, the Baltimore–Washington Metropolitan Area had a population exceeding 8.5 million residents in 2010, the fourth-largest combined statistical area in the country.
According to the 2010 Census, the population of Washington, D.C., was 50.7% Black or African American, 38.5% White, 3.5% Asian, and 0.3% Native American. Individuals from other races made up 4.1% of the District's population while individuals from two or more races made up 2.9%. In addition, Hispanics of any race made up 9.1% of the District's population. About 16% of D.C. residents were age 18 or younger as of 2010; lower than the U.S. average of 24%. However, at 34 years old, the District also had the lowest median age when compared to the 50 states. As of 2010, there were an estimated 81,734 foreign immigrants living in Washington, D.C. Major sources of immigration include individuals from El Salvador, Vietnam, and Ethiopia, with a concentration of Salvadorans in the Mount Pleasant neighborhood.
Unique among cities with a high percentage of African Americans, Washington has had a significant black population since the city's creation. This is partly a result of the manumission of slaves in the Upper South after the American Revolutionary War. The free black population in the region climbed from an estimated 1% before the war to 10% by 1810. By 1860, approximately 80% of the city's 11,000 African American residents were free persons. Black residents composed about 30% of the District's total population between 1800 and 1940.
Washington's African American population reached a peak of 70% by 1970. Since then, however, the percentage of black residents has steadily declined due to many African Americans leaving the city for the surrounding suburbs. At the same time, the city's white population has steadily increased, due in part to the effects of gentrification in many of Washington's traditionally African American neighborhoods. This is evident in an 11.5% decrease in the black population and a 31.4% increase in the non-Hispanic white population since 2000. Even still, Washington, D.C., is a top destination for African American professionals who are moving to the area in a "New Great Migration."
Researchers using data from the 2010 Census revealed that there were 4,822 same-sex couples in the District of Columbia, about 2% of total households. The city council passed legislation in 2009 authorizing same-sex marriage and the District began issuing marriage licenses to same-sex couples in March 2010.
A report published in 2007 found that about one-third of District residents are functionally illiterate, compared to a national rate of about one in five. This is attributed in part to immigrants who are not proficient in English. In contrast to the high rate of functional illiteracy, 50% of D.C. residents have at least a four-year college degree. In 2006, D.C. residents had a personal income per capita of $55,755, higher than any of the 50 U.S. states. However, 19% of residents were below the poverty level in 2005, higher than any state except Mississippi. According to data from 2008, more than half of District residents identify as Christian: 28% of residents are Baptists, 13% are Roman Catholic, and 31% are members of other Christian denominations. Residents who practice other faiths make up 6% of the population and 18% do not adhere to a religion.
Over 90% of D.C. residents have health insurance coverage; the second-highest rate in the nation. This is due in part to city programs that help provide insurance to low-income individuals who do not qualify for other types of coverage. A 2009 report found that at least 3% of District residents have HIV or AIDS, which the U.S. Centers for Disease Control and Prevention (CDC) characterizes as a "generalized and severe" epidemic.
During the violent crime wave of the early 1990s, Washington, D.C., was known as the murder capital of the United States and often rivaled New Orleans in the number of homicides. The number of murders peaked in 1991 at 479, but the level of violence declined drastically in the 1990s. By 2011, the annual murder count in the city had declined to 108, the lowest total since 1963. In total, reports of violent crimes and property crimes have both declined by half since 1993.
Like most large cities, crime is highest in areas associated with illegal drugs and gangs. A 2010 study found that 5% of city blocks contributed to over one-quarter of the District's total crime. The more affluent neighborhoods of Northwest Washington are typically safe, but reports of violent crime increase in poorer neighborhoods generally concentrated in the eastern portion of the city. Approximately 60,000 residents are ex-convicts.
Many neighborhoods such as Columbia Heights and Logan Circle are becoming safer and vibrant. However, incidents of robberies and thefts have remained higher in these areas due to increased nightlife activity and greater numbers of affluent residents. While instances of property crime remain high, reports are still half the level cited during the mid-1990s, and the patterns of theft continue to disperse to the north and east of downtown.
On June 26, 2008, the Supreme Court of the United States held in District of Columbia v. Heller that the city's 1976 handgun ban violated the Second Amendment right to gun ownership. However, the ruling does not prohibit all forms of gun control; laws requiring firearm registration remain in place, as does the city's assault weapon ban.