Founded in 1843, Atchison County is one of 114 counties in the state of Missouri. Historically, Atchison County was formed from Holt County, part of the Platte Purchase. The city of Rock Port is the county seat. With FIPS code of 5, Atchison County has a population of 5,234 and area of 545 square miles (1,412 km2).
List of all cities in Atchison County, MO alphabetically
| City/Town | Postal Code | Area Code |
| Fairfax, MO | 64446 | 660 |
| Rock Port, MO | 64482 | 660 |
| Tarkio, MO | 64491 | 660 |
| Watson, MO | 64496 | 660 |
| Westboro, MO | 64498 | 660 |