He later purchased another in Northumberland County at Machodoc Creek, which empties into the Potomac River. This tract was patented on 18 October 1657, and repatented the following year on 5 June 1658 as 2,000 acres (8 km²). Upon this tract became what was known in later generations as the estates "Mount Pleasant" and "Lee Hall". He then acquired 4,000 acres (16 km²) farther up the Potomac, near where the city of Washington, D.C., would rise, in what was then Westmoreland, now Fairfax County. One of these would eventually become the site of Mount Vernon.