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.

MWCOG provides a forum for discussion and the development of regional responses to issues regarding the environment, transportation, public safety, homeland security, affordable housing, community planning, and economic development.

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