16 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Atchison | 1 | 10,535 | 10,872 | -0.63% | 1,314 | 8.02 | City |
| Shannon township | 2 | 1,108 | 1,144 | -0.36% | 21 | 52.34 | Township |
| Mount Pleasant township | 3 | 843 | 860 | -0.35% | 18 | 47.74 | Township |
| Lancaster township | 4 | 726 | 749 | -0.55% | 12 | 60.19 | Township |
| Center township | 5 | 611 | 620 | 0% | 11 | 53.51 | Township |
| Grasshopper township | 6 | 492 | 505 | -0.2% | 7 | 65.73 | Township |
| Effingham | 7 | 476 | 496 | -0.83% | 769 | 0.62 | City |
| Kapioma township | 8 | 247 | 255 | -0.4% | 5 | 47.45 | Township |
| Lancaster | 9 | 235 | 245 | -0.84% | 1,181 | 0.20 | City |
| Kickapoo Site 5 | 10 | 170 | 75 | 6.92% | 227 | 0.75 | CDP |
| Muscotah | 11 | 154 | 156 | 0% | 462 | 0.33 | City |
| Kickapoo Tribal Center | 12 | 114 | 155 | -4.2% | 59 | 1.94 | CDP |
| Kickapoo Site 1 | 13 | 94 | 92 | 0% | 188 | 0.50 | CDP |
| Kickapoo Site 7 | 14 | 78 | 61 | 8.33% | 154 | 0.51 | CDP |
| Huron | 15 | 70 | 74 | -1.41% | 972 | 0.07 | City |
| Kickapoo Site 2 | 16 | 27 | 57 | 3.85% | 32 | 0.85 | CDP |
Atchison is the largest city in Atchison County, with a population of 10,535.
Kickapoo Site 2 is the smallest city in Atchison County.
There are 16 cities in Atchison County, Kansas.