Harper County is a county located in the U.S. state of Oklahoma. As of the 2020 census, the population was 3,272, making it the third-least populous county in Oklahoma. The county seat is Buffalo. It was created in 1907 from the northwestern part of Woodward County, and named for Oscar Green Harper, who was clerk of the Oklahoma Constitutional Convention.

Woodward County is a county located in the U.S. state of Oklahoma. As of the 2020 census, the population was 20,470. Its county seat is Woodward.