Harrison County is a county located in the northwest portion of the U.S. state of Missouri. As of the 2020 census, the population was 8,157. It's county seat is Bethany. The county was organized February 14, 1845, and named for U.S. Representative Albert G. Harrison of Missouri.

Bethany is a city in, and the county seat of, Harrison County, Missouri, United States, approximately midway between Kansas City and Des Moines on Interstate 35. The population was 2,915 at the 2020 census.