For many millennia, the Great Plains of North America was inhabited by nomadic Native Americans.

In 1802, Spain returned most of the land to France, but keeping title to about 7,500 square miles.

In 1803, most of the land for modern-day Kansas was acquired by the United States from France as part of the 828,000 square mile Louisiana Purchase for 2.83 cents per acre.

During the American Civil War, when Davis became president of the Confederacy, attempts were made to change the county's name, but both failed.

In 1888 the county was renamed in honor of John W. Geary, an early Governor of the Kansas Territory.

Geary County is part of the Manhattan, KS Metropolitan Statistical Area.

The party's presidential candidates have failed to win the county only seven times from 1880 to the present day, the last of these occurring in 1964.

Geary County was a prohibition, or "dry", county until the Kansas Constitution was amended in 1986 and voters approved the sale of alcoholic liquor by the individual drink with a 30% food sales requirement.

† means a community is designated a Census-Designated Place (CDP) by the United States Census Bureau.