| | Atchison, KS | Shawnee, KS | United States |
| Population | 10,773 | 67,021 | 329,725,481 |
| Female Population | 52.5% | 51.5% | 50.5% |
| Male Population | 47.5% | 48.5% | 49.5% |
| Median Age | 31.1 | 37.4 | 38.4 |
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| Population - 2010 | 10,968 | 62,316 | 309,327,143 |
| Population - 2000 | 10,232 | 47,996 | 285,036,114 |
| Population - 1990 | 10,656 | 37,993 | 251,960,433 |
| Pop. 2000 to Now | 1.9% | 38.1% | 15.6% |
| Pop. 1990 to Now | -2.2% | 74.5% | 30.8% |
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| Population Density | 1,345.5 | 1,596.7 | 93.4 |
| Land Area | 8.0 | 42.0 | 3,531,905.4 |
| Water Area | 0.5 | 0.9 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Atchison, KS | Shawnee, KS | United States |
| Age 0 to 4 | 5.0% | 6.4% | 5.9% |
| Age 5 to 9 | 6.9% | 8.1% | 6.1% |
| Age 10 to 14 | 7.8% | 6.4% | 6.6% |
| Age 15 to 17 | 4.8% | 4.4% | 3.9% |
| Age 18 to 20 | 10.8% | 3.5% | 4.0% |
| Age 21 to 24 | 7.1% | 5.0% | 5.2% |
| Age 25 to 34 | 11.4% | 12.8% | 13.8% |
| Age 35 to 44 | 9.7% | 14.0% | 12.9% |
| Age 45 to 54 | 10.1% | 14.1% | 12.6% |
| Age 55 to 59 | 6.7% | 6.0% | 6.7% |
| Age 60 to 64 | 5.7% | 5.5% | 6.3% |
| Age 65 to 74 | 7.7% | 8.8% | 9.6% |
| Age 75 to 84 | 3.5% | 3.4% | 4.5% |
| Age 85 and over | 2.7% | 1.7% | 1.9% |
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| Race | | | |
| | Atchison, KS | Shawnee, KS | United States |
| White | 83.5% | 80.8% | 59.4% |
| Black | 3.7% | 4.9% | 12.2% |
| Asian | 0.7% | 3.4% | 5.6% |
| Native American | 0.2% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 7.4% | 2.9% | 3.2% |
| Hispanic | 4.6% | 7.9% | 18.4% |
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| Marriage & Family | | | |
| | Atchison, KS | Shawnee, KS | United States |
| Married Population | 36.7% | 60.6% | 49.8% |
| Currently Married | 36.3% | 59.8% | 48.0% |
| Married but Separated | 0.4% | 0.8% | 1.8% |
| Single Population | 63.3% | 39.4% | 50.2% |
| Never Married | 43.6% | 27.3% | 33.8% |
| Divorced | 13.4% | 8.9% | 10.8% |
| Widowed | 6.2% | 3.2% | 5.6% |
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| Household Size | 2.54 | 2.66 | 2.60 |
| Households | 3,652 | 25,027 | 124,010,992 |
| Family Households | 2,349 | 17,829 | 80,755,759 |
| Married couple, w/children | 26.4% | 38.6% | 30.5% |
| Married couple, no children | 37.5% | 46.8% | 42.9% |
| Non Family Households | 1,303 | 7,198 | 43,255,233 |
| Single householder, w/children | 24.1% | 9.5% | 15.8% |
| Single householder, no children | 11.9% | 5.1% | 10.8% |