Fort Loudon is located in western Franklin County in the valley of the West Branch
Conococheague Creek, with Cove Mountain to the west,
Blue Mountain to the north, and Parnell Knob to the east.
U.S. Route 30, the
Lincoln Highway, passes through the community, leading west to
McConnellsburg and east to
Chambersburg, the Franklin County seat.
Pennsylvania Route 75 crosses US 30 southwest of the town center, leading north up the Path Valley to
Fannettsburg and south to
Mercersburg. According to the
U.S. Census Bureau, the Fort Loudon CDP has an area of , all land. ==Demographics==