32 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Decatur | 1 | 37,762 | 36,934 | 0.71% | 1,170 | 32 | Township |
| Decatur | 2 | 10,140 | 9,936 | 0.34% | 1,662 | 6 | City |
| Monroe | 3 | 9,127 | 8,769 | 0.98% | 178 | 51 | Township |
| Geneva | 4 | 7,633 | 7,500 | 0.3% | 137 | 56 | Township |
| Monroe | 5 | 6,640 | 5,629 | 2.37% | 251 | 26 | Township |
| Root | 6 | 6,171 | 6,045 | 0.1% | 169 | 36 | Township |
| Monroe | 7 | 6,010 | 5,643 | 1.16% | 108 | 56 | Township |
| Monroe | 8 | 5,459 | 5,273 | 0.61% | 150 | 36 | Township |
| Berne | 9 | 4,373 | 4,183 | 0.74% | 1,891 | 2 | City |
| Monroe | 10 | 3,822 | 3,869 | -0.13% | 93 | 41 | Township |
| Monroe | 11 | 3,585 | 3,500 | 0.48% | 118 | 30 | Township |
| Monroe | 12 | 3,437 | 3,454 | -0.12% | 118 | 29 | Township |
| Monroe | 13 | 2,927 | 2,870 | 0.52% | 122 | 24 | Township |
| Monroe | 14 | 2,077 | 1,966 | 1.07% | 84 | 25 | Township |
| Monroe | 15 | 1,663 | 1,645 | 0.36% | 47 | 36 | Township |
| Blue Creek | 16 | 1,602 | 1,566 | 0.13% | 66 | 24 | Township |
| Monroe | 17 | 1,573 | 1,489 | 0.77% | 45 | 35 | Township |
| Jefferson | 18 | 1,415 | 1,377 | 0.35% | 59 | 24 | Township |
| Monroe | 19 | 1,325 | 1,322 | 0.23% | 69 | 19 | Township |
| Geneva | 20 | 1,300 | 1,260 | 0.54% | 1,178 | 1 | Town |
| St. Marys | 21 | 1,294 | 1,264 | 0.15% | 53 | 25 | Township |
| French | 22 | 1,284 | 1,253 | 0.23% | 54 | 24 | Township |
| Monroe | 23 | 1,169 | 1,148 | 0.52% | 49 | 24 | Township |
| Preble | 24 | 1,056 | 1,030 | 0.28% | 44 | 24 | Township |
| Hartford | 25 | 1,012 | 985 | 0.2% | 42 | 24 | Township |
| Kirkland | 26 | 971 | 942 | 0.52% | 40 | 24 | Township |
| Union | 27 | 929 | 901 | 0.43% | 38 | 25 | Township |
| Monroe | 28 | 908 | 884 | 0.44% | 1,335 | 1 | Town |
| Monroe | 29 | 637 | 608 | 0.95% | 17 | 38 | Township |
| Monroe | 30 | 624 | 641 | -0.32% | 15 | 42 | Township |
| Monroe | 31 | 365 | 352 | 0.83% | 10 | 37 | Township |
| Vera Cruz | 32 | 71 | 68 | 1.43% | 703 | 0 | Town |
Decatur is the largest city in Adams County, with a population of 37,762.
Vera Cruz is the smallest city in Adams County, with a population of 71.
There are 32 cities in Adams County, Indiana.