Atchison County is the northwesternmost county in the U.S. state of Missouri. As of the 2020 census, the county had a population of 5,305. Its county seat is Rock Port. It was originally known as Allen County when it was detached from Holt County in 1843. The county was officially organized on February 14, 1845, and named for U.S. Senator David Rice Atchison from Missouri.
Geography
According to the U.S. Census Bureau, the county has a total area of , of which is land and (0.5%) is water.
Atchison's western boundary for the most part is the Missouri River and Nebraska. An 1867 flood straightened a bend in the river north of Watson. Both Nebraska and Missouri claimed the 5,000 acre McKissick Island that extends almost two miles into Atchison County. The Supreme Court in 1904 decided that the land belongs to Nebraska. The only way Nebraskans can reach it by road is to cross the Missouri River and then travel through Missouri.
The State Line Slough (Missouri) stream is in Atchison County.
Adjacent counties
- Fremont County, Iowa (north)
- Page County, Iowa (northeast)
- Nodaway County (east)
- Holt County (south)
- Richardson County, Nebraska (southwest)
- Nemaha County, Nebraska (west)
- Otoe County, Nebraska (northwest)
Major highways
Source:
- frameless|20x20px Interstate 29
- frameless|20x20px U.S. Route 59
- frameless|20x20px U.S. Route 136
- frameless|20x20px U.S. Route 275
- frameless|20x20px Route 46
- frameless|20x20px Route 111
Transit
- Jefferson Lines