As of April 2020 there were 3,197,076 people in Northern Virginia; approximately 37 percent of the state’s population.
These population counts include all counties within Virginia that are part of the Washington-Arlington-Alexandria, DC-VA-MD-WV Metropolitan Statistical Area or the Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area as defined by the U.S. Office of Management and Budget within the Executive Office of the President of the United States.
Of the 3,159,639 people in Northern Virginia in the 2019 estimates, 2,776,960 lived in “central” counties, or those counties and equivalent entities as delineated by the U.S. Office of Management and Budget as forming part of the urban core of the Washington Metropolitan Statistical Area. These counties include Arlington, Fairfax, Fauquier, Loudoun, Prince William, Stafford and the independent cities of Alexandria, Fairfax, Falls Church, Manassas, Manassas Park and Fredericksburg
An additional 390,679 people lived in counties of the Washington Metropolitan Statistical Area or the Baltimore-Washington Combined Statistical Area not considered “central.” These counties, largely considered exurban or undergoing suburban change, include Clarke, Culpeper, Frederick, Madison, Rappahannock, Spotsylvania, Warren, and the independent city of Winchester.
In addition, there are counties outside of the Washington Metropolitan Area that under more broad definitions are referred to as being part of Northern Virginia. The University of Virginia Weldon Cooper Center for Public Service categorizes King George County as part of Northern Virginia, though the county was removed from the Washington Metropolitan Area in 2003. King George County and Orange County also include areas, such as Lake of the Woods, where the cross-commuting interchange with the Washington Metropolitan Area is high enough to merit inclusion in the Metropolitan Area, although more far-flung parts of these counties still cause the county-wide commuter interchange to fall below the threshold for inclusion in the Washington Metropolitan Area or Washington-Baltimore Combined Statistical Area. The demographic figures above do not include population counts for these two counties.