[2] Following an election on May 22, 1909, Harmon County was created by proclamation of Governor Lee Cruce on June 2.

County offices operated in rented space until a courthouse was built in Hollis in 1926.

In 1930, the U.S. Supreme Court ruled that the boundary between Texas and Oklahoma was actually 3,800 feet (1,200 m) farther east than originally believed.

It returned the disputed land to Texas, reducing the county's area to its present size.

[4] A railroad built from Altus, Oklahoma to the Texas state line came to Hollis and Gould in 1910.

The line was built by the Altus, Wichita Falls and Hollis Railway (later acquired by the Missouri, Kansas and Texas Railroad).

By 1930, farmers had sizable holdings of cattle, poultry, horses, mules, swine, sheep and goats.