Prince William County was established in 1730/31 from Stafford and King George Counties. Descendant Counties include Fairfax (Loudoun) in 1742; and Fauquier in 1759. The boundaries of the newly-created Prince William County were described in a 1730 Act of the General Assembly as “...above Chopawansick Creek, on Potomack river, and Deep run on Rappahannock river and a south west line to be made, from the head of the north branch of the said creek, to the head of the said Deep run... and known by the name of Prince William County.” (9 Hening 244.)