Jamestown was a region on the southwest side of the Seigniory of Beauharnois. It was bounded on the northwest by the Châteauguay River, on the southwest by Hinchinbrooke Township in the County of Huntingdon, on the south east by Russelltown region (boundary line was the present Grimshaw Road and Rang Savary) and on the northeast by South Georgetown region (boundary line was the Brysonville Sideroad).