In 1738, about 30 farms were established as part of Lord Fairfax's 9,000 acre Patterson Creek Manor near present day Burlington, West Virginia. Returning in 1747, he first settled at Belvoir, (the ruins of which lie on the grounds of Fort Belvoir), which was built by his agent Col.William Fairfax. He was active developing his land, and collecting ground rents.
He later moved to the Shenandoah Valley in 1752, fixing his residence at Greenway Court near White Post in Clarke County, located closer to his undeveloped land. Here, Lord Fairfax lived in a style of liberal hospitality, frequently indulging in the diversion of the chase. He served as county lieutenant and as justice of the peace for Frederick County which then included Clarke.
Lord Fairfax was the only resident peer in colonial America. In 1748, he made the acquaintance of George Washington, a distant relative of the Yorkshire Fairfax family who was then a youth of 16. Impressed with Washington's energy and talents, Lord Fairfax employed him to survey his lands lying west of the Blue Ridge.
Though a frank and avowed Loyalist, he was never insulted or molested by the Whigs. His title and immense domain, consisting of 5,282,000 acres (21,380 km²), descended to his only surviving brother, Robert Fairfax, 7th Lord Fairfax of Cameron, who died at Leeds Castle, England, in 1793. However, the domain was in possession of Lord Thomas Fairfax during the American Revolutionary War and it was confiscated during the hostilities, by the Virginia Act of 1779. Robert Fairfax was awarded ₤13,758 in 1792, by Act of Parliament for the relief of American Loyalists.