Prince William County is located on the Potomac River in the Commonwealth of Virginia. Its county seat is the independent city of Manassas. A part of Northern Virginia, Prince William County is included in the Washington-Arlington-Alexandria, DC-VA-MD-WV Metropolitan Statistical Area. In 2012 it had the seventh highest income of any county in the United States. It was the first minority-majority county in Virginia, with Hispanic (of any race, mostly from Central and South America), African American, and Asian being the chief groups.
Prince William County was created by an act of the General Assembly of the colony of Virginia in 1731; it was organized largely from the western section of Stafford County as well as a section of King George County. The area encompassed by the act creating Prince William County originally included all of what later became the counties of Arlington, Fairfax, Fauquier, and Loudoun; and the independent cities of Alexandria, Fairfax, Falls Church, Manassas, and Manassas Park. These later became independent jurisdictions. The county was named for Prince William, Duke of Cumberland, the third son of King George II.
The National Museum of the Marine Corps is located in Triangle, Virginia and is free to the public. The Historic Preservation Division of Prince William County also operates five museums: Rippon Lodge Historic Site, Brentsville Historic Centre, Bristoe Station Battlefield Heritage Park, Lucasville Historic Site, and Ben Lomond Historic Site.
Two National Parks lie within the county. Prince William Forest Park was established as Chopawamsic Recreational Demonstration Area in 1936 and is located in eastern Prince William County. This is the largest protected natural area in the Washington, D.C. metropolitan region at over 15,000 acres (6,070 ha). Manassas National Battlefield Park, located north of Manassas in Prince William County, preserves the site of two major American Civil War battles: the First Battle of Manassas on July 21, 1861, and the Second Battle of Manassas which was fought between August 28 and August 30, 1862. Outside the South, these battles are commonly referred to as the first and second battles of Bull Run.