Fairfax, Virginia, formally the City of Fairfax, is an independent city in the Commonwealth of Virginia in the United States. As of the 2020 census, the population was 24,146. It is the county seat of Fairfax County, Virginia. The city, which is part of both the Washington metropolitan area and Northern Virginia, is located 14 miles west of Washington, D.C. The Washington Metro's Orange Line serves Fairfax through its Vienna station, which is a mile northeast of Fairfax.