In 1896 it was designated as a county in Oklahoma Territory under a ruling by the US Supreme Court.

[3] The rural Greer County is home to Quartz Mountain State Park, near the community of Lone Wolf, Oklahoma.

[4] Its population has declined since 1930 due to changes in agriculture and migration to cities for work.

After a dispute over the 1819 Adams-Onís Treaty and the related 1828 Treaty of Limits, the governments of both the United States and the state of Texas claimed ownership of some 1.5 million acres (6,100 km2) in what was then operated as Greer County, Texas.

Mechanization of agriculture reduced the need for farm labor, and the population has declined as people migrated to cities for work.

[6] Western Greer County lies in the Gypsum Hills, while the eastern one-third is in the Red Bed Plains physiographic region.

Livestock raised includes cattle, horses, mules, swine, sheep and goats.

[4] The Oklahoma State Reformatory is located in Granite in the county and provides some jobs.