[2] 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.

[3] During the late 19th century, the area now known as Harper County was part of the Cherokee Outlet, reserved for use by the Cherokee Nation by treaties in 1828 and 1835, The U.S. government opened the outlet for settlement by non-Indians in 1893.

It was named for Oscar Green Harper, who was a local resident, school teacher, and served as clerk of the Oklahoma Constitutional Convention.

[3] A 1908 election was held to determine whether Buffalo or Doby Springs would become the county seat.

[3] Other ghost towns in the county are Paruna, Flat, Avis, Readout, Cross, Alto, Cupid, and Stockholm.

[3] Railroads first came to Harper County in 1912, when the Wichita Falls and Northwestern Railway, a subsidiary of the Missouri, Kansas and Texas Railway (MK&T), built a line through Dunlap, May, Laverne, and Rosston.

The Atchison, Topeka and Santa Fe Railway acquired the B&NW in 1920.

This dominance is also reflected in the large voter registration advantage that Republicans have in the county.