Harmon county is located in the extreme southwestern corner of Oklahoma and calls Hollis its county seat.
The Red River forms just over half of the southern county line. Other waterways include the Salt Fork of the Red River which meanders west to east through the midsection of the county. The Elm Fork of the Red River makes a brief appearance near the county's northwest corner.
Of interest to history buffs is the Harmon County Courthouse which is listed in the National Register of Historic Places.
The county population on July 1, 1999, was 3,336, a decrease of 457 over the 1990 census.