32 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Decatur | 1 | 37,496 | 36,934 | 0.71% | 1,162 | 32 | Township |
| Decatur | 2 | 10,106 | 9,936 | 0.34% | 1,656 | 6 | City |
| Monroe | 3 | 9,038 | 8,769 | 0.99% | 176 | 51 | Township |
| Geneva | 4 | 7,610 | 7,500 | 0.3% | 136 | 56 | Township |
| Monroe | 5 | 6,486 | 5,629 | 2.43% | 245 | 26 | Township |
| Root | 6 | 6,165 | 6,045 | 0.1% | 169 | 36 | Township |
| Monroe | 7 | 5,941 | 5,643 | 1.18% | 107 | 56 | Township |
| Monroe | 8 | 5,426 | 5,273 | 0.61% | 149 | 36 | Township |
| Berne | 9 | 4,341 | 4,183 | 0.72% | 1,877 | 2 | City |
| Monroe | 10 | 3,827 | 3,869 | -0.13% | 93 | 41 | Township |
| Monroe | 11 | 3,568 | 3,500 | 0.48% | 118 | 30 | Township |
| Monroe | 12 | 3,441 | 3,454 | -0.12% | 118 | 29 | Township |
| Monroe | 13 | 2,912 | 2,870 | 0.52% | 121 | 24 | Township |
| Monroe | 14 | 2,055 | 1,966 | 1.08% | 83 | 25 | Township |
| Monroe | 15 | 1,657 | 1,645 | 0.36% | 47 | 36 | Township |
| Blue Creek | 16 | 1,600 | 1,566 | 0.13% | 66 | 24 | Township |
| Monroe | 17 | 1,561 | 1,489 | 0.77% | 45 | 35 | Township |
| Jefferson | 18 | 1,410 | 1,377 | 0.36% | 59 | 24 | Township |
| Monroe | 19 | 1,322 | 1,322 | 0.23% | 69 | 19 | Township |
| Geneva | 20 | 1,293 | 1,260 | 0.47% | 1,171 | 1 | Town |
| St. Marys | 21 | 1,292 | 1,264 | 0.16% | 53 | 25 | Township |
| French | 22 | 1,281 | 1,253 | 0.23% | 54 | 24 | Township |
| Monroe | 23 | 1,163 | 1,148 | 0.52% | 49 | 24 | Township |
| Preble | 24 | 1,053 | 1,030 | 0.29% | 44 | 24 | Township |
| Hartford | 25 | 1,010 | 985 | 0.2% | 42 | 24 | Township |
| Kirkland | 26 | 966 | 942 | 0.52% | 40 | 24 | Township |
| Union | 27 | 925 | 901 | 0.43% | 37 | 25 | Township |
| Monroe | 28 | 904 | 884 | 0.44% | 1,329 | 1 | Town |
| Monroe | 29 | 631 | 608 | 0.96% | 16 | 38 | Township |
| Monroe | 30 | 626 | 641 | -0.32% | 15 | 42 | Township |
| Monroe | 31 | 362 | 352 | 0.84% | 10 | 37 | Township |
| Vera Cruz | 32 | 70 | 68 | 0% | 693 | 0 | Town |
Decatur is the largest city in Adams County, with a population of 37,496.
Vera Cruz is the smallest city in Adams County, with a population of 70.
There are 32 cities in Adams County, Indiana.