Greer County, Oklahoma

Greer County, Oklahoma
Greer County Courthouse in Mangum
Location in the U.S. state of Oklahoma
Oklahoma's location in the U.S.
Founded	1896
Seat	Mangum
Largest city	Mangum
Area
• Total	644 sq mi (1,668 km2)
• Land	639 sq mi (1,655 km2)
• Water	4.3 sq mi (11 km2), 0.7%
Population (est.)
• (2013)	6,171
• Density	9.8/sq mi (4/km²)
Congressional district	3rd
Time zone	Central: UTC-6/-5
Website	greer.okcounties.org

Greer County is a county located along the southwest border of the U.S. state of Oklahoma. As of the 2010 census, the population was 6,239. Its county seat is Mangum. From 1860 to 1896, the state of Texas claimed an area known as Greer County, Texas, which included present-day Greer County along with neighboring areas. In 1896 it was designated as a county in Oklahoma Territory under a ruling by the US Supreme Court.

The rural Greer County is home to Quartz Mountain Nature Park, near the community of Lone Wolf, Oklahoma (known until 2002 as Quartz Mountain State Park). It is also home to the Oklahoma State Reformatory, located in Granite. 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 (6,000 km²) in what was then operated as Greer County, Texas. The county was named for former Texas lieutenant governor, John A. Greer. Litigation followed, and in the case of United States v. State of Texas 162 U.S. 1 (1896), with a ruling issued on March 16, the Supreme Court, having original jurisdiction over the case, decided in favor of the United States.