[2] The county is named for the Canadian River, which forms part of its southern border.

The river may have been named for early European explorers who were fur traders and trappers from New France, or pre-1763 colonial Canada.

[3] Canadian County is part of the Oklahoma City metropolitan statistical area.

In 1859, the United States expelled the Caddo Nation of Louisiana from its Brazos reservation in Texas and relocated it to what would eventually become Canadian County, Oklahoma.

[4][5] Showetat, the last hereditary chief of the Caddo, set up his camp here and is considered Canadian County's first permanent resident.

)[6] The federal government relocated the Wichita tribe to this same part of Indian Territory in 1861.

By the Treaty of Medicine Lodge, the United States assigned the land west of the Caddo and Wichita to the Cheyenne and Arapaho tribes.

The county was the location of the last great battle of the Cheyenne and Arapaho against United States Army forces.

[9] The Canadian River enters the western border of the county about 11 miles (18 km) north of the southwest corner at an elevation of 1,370 feet (420 m) and flows southeast about 16 miles (26 km), where it becomes the southern border of the county.

[10] The Cimarron River does not flow through the county, but drains part of the northeastern area via its tributaries: Kingfisher, Dead Indian, Uncle John, Cottonwood, Soldier, and Deer creeks.

Elementary: The following sites in Canadian County are listed on the National Register of Historic Places: