Atchison County | |
|---|---|
Atchison County Courthouse in Atchison (2023) | |
Location within the U.S. state of Kansas | |
Kansas's location within the U.S. | |
| Coordinates: 39°32′N 95°18′W / 39.533°N 95.300°W | |
| Country | |
| State | |
| Founded | August 25, 1855 |
| Named for | David Rice Atchison |
| Seat | Atchison |
| Largest city | Atchison |
| Area | |
| • Total | 434 sq mi (1,120 km2) |
| • Land | 431 sq mi (1,120 km2) |
| • Water | 2.6 sq mi (7 km2) 0.6% |
| Population (2020) | |
| • Total | 16,348 |
| • Density | 37.9/sq mi (14.6/km2) |
| Time zone | UTC−6 (Central) |
| • Summer (DST) | UTC−5 (CDT) |
| Area code | 913 |
| Congressional district | 2nd |
| Website | AtchisonCountyKS.org |
Atchison County (county code AT) is a county in northeastern Kansas, in the Central United States. In 2020, 16,348 people lived there. Its county seat is Atchison. Atchison is also the biggest city in the county. The county is named after David Rice Atchison, a United States Senator from Missouri.
The U.S. Census Bureau says that the county has a total area of 434 square miles (1,120 km2). Of that, 431 square miles (1,120 km2) is land and 2.6 square miles (6.7 km2) (0.6%) is water. It is the fourth-smallest county by area in Kansas.
On July 4, 1804, to mark Independence Day, the Lewis and Clark Expedition named Independence Creek near the city of Atchison (see Timeline of the Lewis and Clark Expedition).
Sources: National Atlas, U.S. Census Bureau
| Historical population | |||
|---|---|---|---|
| Census | Pop. | %± | |
| 1860 | 7,729 | — | |
| 1870 | 15,507 | 100.6% | |
| 1880 | 26,668 | 72.0% | |
| 1890 | 26,758 | 0.3% | |
| 1900 | 28,606 | 6.9% | |
| 1910 | 28,107 | −1.7% | |
| 1920 | 23,411 | −16.7% | |
| 1930 | 23,945 | 2.3% | |
| 1940 | 22,222 | −7.2% | |
| 1950 | 21,496 | −3.3% | |
| 1960 | 20,898 | −2.8% | |
| 1970 | 19,165 | −8.3% | |
| 1980 | 18,397 | −4.0% | |
| 1990 | 16,932 | −8.0% | |
| 2000 | 16,774 | −0.9% | |
| 2010 | 16,924 | 0.9% | |
| 2020 | 16,348 | −3.4% | |
| U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010-2020 | |||

Atchison County is in the Atchison, KS Micropolitan Statistical Area. It is also included in the Kansas City-Overland Park-Kansas City, MO-KS Combined Statistical Area.
Atchison County has been a swing county for most of its history. It has had multiple extended streaks of being a bellwether county, the first running from 1896 to 1936. After voting more Republican than the nation in the 1940s & voting for losing candidate Richard Nixon in 1960, another bellwether streak ran from 1964 to 2004. Since then, the county has become significantly more Republican, with Barack Obama failing to win the county in both of his victories & Hillary Clinton losing it by over 30 percent to Donald Trump in 2016.
| Year | Republican | Democratic | Third Parties |
|---|---|---|---|
| 2024 | 67.4% 4,911 | 30.2% 2,201 | 2.4% 172 |
| 2020 | 65.9% 4,906 | 31.7% 2,359 | 2.4% 175 |
| 2016 | 61.6% 4,049 | 30.3% 1,989 | 8.2% 537 |
| 2012 | 58.7% 3,917 | 38.5% 2,567 | 2.9% 190 |
| 2008 | 52.7% 3,791 | 45.1% 3,241 | 2.2% 159 |
| 2004 | 54.5% 3,880 | 43.8% 3,120 | 1.7% 118 |
| 2000 | 49.0% 3,378 | 46.0% 3,171 | 5.1% 351 |
| 1996 | 43.3% 2,828 | 44.8% 2,926 | 12.0% 784 |
| 1992 | 33.5% 2,521 | 39.3% 2,959 | 27.2% 2,050 |
| 1988 | 49.0% 3,243 | 48.0% 3,177 | 2.9% 194 |
| 1984 | 62.5% 4,537 | 36.4% 2,641 | 1.1% 77 |
| 1980 | 53.9% 4,084 | 40.4% 3,063 | 5.7% 434 |
| 1976 | 48.3% 4,030 | 49.2% 4,108 | 2.5% 206 |
| 1972 | 67.8% 5,471 | 29.8% 2,404 | 2.4% 191 |
| 1968 | 46.0% 3,644 | 42.7% 3,379 | 11.4% 899 |
| 1964 | 38.2% 3,147 | 61.2% 5,037 | 0.6% 45 |
| 1960 | 52.3% 4,793 | 47.3% 4,336 | 0.3% 31 |
| 1956 | 64.1% 5,608 | 35.8% 3,134 | 0.1% 9 |
| 1952 | 64.6% 6,004 | 35.3% 3,283 | 0.1% 9 |
| 1948 | 51.0% 4,141 | 48.2% 3,910 | 0.8% 62 |
| 1944 | 58.6% 4,731 | 41.2% 3,325 | 0.3% 20 |
| 1940 | 56.1% 5,921 | 43.2% 4,557 | 0.8% 82 |
| 1936 | 47.6% 5,312 | 52.1% 5,817 | 0.3% 31 |
| 1932 | 45.2% 4,778 | 53.3% 5,640 | 1.5% 157 |
| 1928 | 63.7% 6,647 | 36.0% 3,756 | 0.4% 37 |
| 1924 | 63.8% 6,246 | 22.5% 2,199 | 13.7% 1,341 |
| 1920 | 65.0% 5,872 | 34.1% 3,082 | 0.9% 77 |
| 1916 | 48.6% 4,624 | 48.7% 4,634 | 2.7% 254 |
| 1912 | 27.4% 1,535 | 43.7% 2,449 | 28.9% 1,618 |
| 1908 | 54.9% 3,244 | 43.9% 2,593 | 1.2% 68 |
| 1904 | 64.3% 3,542 | 33.6% 1,854 | 2.1% 117 |
| 1900 | 55.5% 3,390 | 43.9% 2,682 | 0.5% 32 |
| 1896 | 52.7% 3,326 | 46.9% 2,963 | 0.4% 28 |
| 1892 | 49.2% 2,666 | 50.8% 2,756 | |
| 1888 | 52.1% 3,219 | 42.1% 2,603 | 5.8% 357 |
