It is the most educated, highest-income, and third-most populous combined statistical area in the United States behind New York City–Newark, NJ and Los Angeles–Long Beach.

[5][6][7][8][9] This is mostly due to their proximity to the area, the size of their commuter population, and by the influence of local broadcasting stations.

[10] The counties and independent cities and their groupings that comprise the area are listed below with their 2012 population estimates.

Founded in 1957, the Metropolitan Washington Council of Governments (MWCOG) is a regional organization of 23 Washington-area local governments, members of the Maryland and Virginia state legislatures, the U.S. Senate, and the U.S. House of Representatives.

Many defense contractors are based in Northern Virginia and Montgomery County, Maryland to be close to the Pentagon in Arlington.