Atchison is a city and county seat of Atchison County, Kansas, United States, and situated along the Missouri River. As of the 2010 census, its population was 11,021.The city is named in honor of David Rice Atchison, United States senator from Missouri, and was the original eastern terminus of the Atchison, Topeka and Santa Fe Railway.Atchison was the birthplace of aviator Amelia Earhart, and the Amelia Earhart Festival is held annually in July.