1. Be it enacted by the General Assembly, That all that part of the county of Loudoun lying between the lower boundary thereof, and a line to be drawn from the mouth of Sugar Land run, to Carter’s mill, on Bull run, shall be, and is hereby added to and made part of the county of Fairfax:  Provided always, That it shall be lawful for the sheriff of the said county of Loudoun to collect and make distress for any public dues or officers fees, which shall remain unpaid by the inhabitants of that part of the said county hereby added to the county of Fairfax, and shall be accountable for the same in like manner as if this act had not been made.

2. And be it further enacted, That it shall be lawful for a majority of the acting justices of the peace for the said county of Fairfax, together with the justices of the county of Loudoun included within the part thus added to the said county of Fairfax, and they are hereby required at a court to be held in the month of April or May next, to fix on a place for holding courts therein at or as near the center thereof (having regard to that part of the county of Loudoun hereby added to the said county of Fairfax) as the situation and convenience will admit of; and thenceforth proceed to erect the necessary public buildings at such place, and until such buildings be completed, to appoint any place for holding courts as they shall think proper.

     3.  This act shall commence and be in force from and after
     the passing thereof.

As at present bounded, the old channel at the mouth of Sugar Land run, at Lowe’s Island,[3] is “the commencement of the line that separates Loudoun from Fairfax County and runs directly across the country to a point on the Bull Run branch of Occoquan River, about three eighths of a mile above Sudley Springs, in Prince William County.”  The Bull Run then forms the boundary between Loudoun and Prince William to its highest spring head in the Bull Run mountain, just below the Cool Spring Gap.  The line then extends to the summit of the mountain, where the counties of Fauquier and Prince William corner.  From the summit of this mountain, a direct line to a point[4] on the Blue Ridge, at Ashby’s Gap, marks the boundary between Loudoun and Fauquier counties.  A devious line, which follows in part the crests of the Blue Ridge until reaching the Potomac below Harpers Ferry, separates Loudoun from Clarke County, Virginia, and Jefferson County, West Virginia, on her western border.  The Potomac then becomes the dividing line between Loudoun County, and Frederick and Montgomery counties, Maryland; “and that State, claiming the whole of the river, exercises jurisdiction over the islands as well as the river.”