Atchison is a city and county seat of Atchison County, Kansas, United States, along the Missouri River. As of the 2020 census, the population of the city was 10,885. The city is named in honor of US Senator David Rice Atchison from Missouri and was the original eastern terminus of the Atchison, Topeka and Santa Fe Railway. Atchison is also the home of Benedictine College.

David Rice Atchison was a mid-19th century Democratic United States Senator from Missouri. He served as President pro tempore of the United States Senate for six years. Atchison served as a major general in the Missouri State Militia in 1838 during Missouri's Mormon War and as a Confederate brigadier general during the American Civil War under Major General Sterling Price in the Missouri Home Guard. Some of Atchison's associates claimed that for 24 hours—Sunday, March 4, 1849, through noon on Monday—he may have been Acting President of the United States. This belief, however, is dismissed by nearly all scholars.