Prince William County was named for William Augustus, duke of Cumberland and third son of King George II. It was formed from Stafford and King George Counties by a statute adopted in 1730, to take effect on 12 March 1731.

The District Court was created in 1788. The purpose of the creation of the District Court was to alleviate congestion in the General Court which had caused unreasonable delays in the adjudication of common law cases. Virginia was divided into eighteen districts, each composed of several counties, plust the district of Kentucky. Courts were held in each district twice yearly and cases were heard from the several counties in that district. The District Court always met at the same place in each district, and its records were kept at that one location. The District Courts were abolished in 1809 and were replaced by the Superior Courts of Law.

The District Court held at Dumfries heard cases originating in the counties of: included Fairfax, Fauquier, Loudoun, and Prince William.

Many pre-Civil War records were lost, destroyed, or stolen by Union troops in 1863 during the Civil War. Sixteen deed books and five will books are missing. This volume was rescued from from the burning courthouse by a member of the 145th Pennsylvania Volunteers.