County in northeast Virginia (population 280,813 per Census 2000), located about 30 miles southwest of Washington,D.C. The county is situated right between the foothills of the Virginia Piedmont and the coastal waters of the lower Potomac River, which is an arm of the Chesapeake Bay below Washington.
The county was named for William of Cumberland, the second son of King George II. The county was formed in 1731. and originally contained all of neighboring Fairfax County, Virginia, Loudoun County, Virginia and Fauquier County, Virginia; it was reduced to its present size of 360 square miles (including Manassas, VA and Manassas Park, VA) in 1759.
The County was a fairly sleepy place until some of the the first shots of the American Civil War were fired in the hamlet of Yorkshire, VA, in the north-central part of the county above wat is now Manassas, VA. This was followed later by the Battle of Second Manassas, and after the war, Manassas became an important rail stop and, eventually, a suburb of Washington.
Other towns in the western part of PWC are Haymarket, VA (one of two towns in PWC) and Gainesville (an unincoporated town at the junction of Interstate 66 and US Highway 29).
The eastern part of the County is dominated by the Interstate 95/US Highway 1 corridor. Just north of 95 is Occoquan, VA, which was a major mail stop during the Civil War, an important industrial town during the 18th century, and is now a restored art town, with many small shops and restaurants. (It's also home to Fairfax County, Virginia's Occoquan Water Treatment Facilities, which is also a major source of water for eastern PWC.)
Woodbridge, VA was the first part of eastern Prince William to be built up, and has some of the oldest commercial developments. The area received a huge boost when Potomac Mills Mall opened in 1986; however, most of the buildings along Route 1 are still empty and/or decrepit-looking. Most of the limited industrial activity in the County is concentrated in this area, and in industrial parks west of Manassas.
Just southwest of Potomac Mills Mall is the planned community of Dale City, VA, which was originally envisioned and built in the 1950s by the Hylton family, who still owns most of the land, and provides certain utilities (water by a contract with Virginia American Water Company, who gets it from Fairfax County, Virginia; sewerage using their own plants). Fun fact: All the streets in the Dale City area have the word "dale" in their name -- if they don't you've strayed into either Woodbridge or Dumfries. Minnieville Road, which runs northeast/southwest through the southern part of the community, is the only exception.
Further south is Dumfries, VA, which is the oldest incorporated town in Virginia, the second of the two in the County. It was a busy port in Colonial days, but the port was silted out, and then abandoned. It's home now to, among other things, the Weems-Botts Museum.
The far southern part of the county is owned by the US Marine Corps, and is part of the Quantico Combat Development Command. The "mainside" of the base is on the eastern part of the land, from Route 1 to the Potomac River.
The rest of the county is still predominantly rural. Most of the farms and fields are in a "rural crescent" stretching from the northern end of the county, along the west side, running through the center of the county near Independent Hill, and ending at the Marine base's borders.