The Washington metropolitan area is the metropolitan area centered on Washington, D.C., the capital of the United States. The area includes all of the federal district and parts of the U.S. states of Maryland and Virginia, along with a small portion of West Virginia.
The U.S. Office of Management and Budget defines the area as the Washington–Arlington–Alexandria, DC–VA–MD–WV metropolitan statistical area, a metropolitan statistical area used for statistical purposes by the United States Census Bureau and other agencies. The area includes as its principal cities Washington as well as the Virginia county of Arlington and city of Alexandria. The Office of Management and Budget also includes the metropolitan statistical area as part of the larger Baltimore–Washington metropolitan area, which has a population of 9,331,587 as of the 2012 Census Estimate.[