26 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hanover | 1 | 21,661 | 18,330 | 1.92% | 754 | 29 | Township |
| Madison | 2 | 17,779 | 18,062 | -0.2% | 310 | 57 | Township |
| Madison | 3 | 11,994 | 12,336 | -0.47% | 1,388 | 9 | City |
| Madison | 4 | 10,511 | 10,193 | 0.81% | 382 | 28 | Township |
| Hanover | 5 | 5,689 | 5,576 | 0.35% | 304 | 19 | Township |
| Hanover | 6 | 3,870 | 3,741 | 0.57% | 1,742 | 2 | Town |
| Madison | 7 | 3,015 | 3,027 | -0.03% | 82 | 37 | Township |
| Madison | 8 | 2,850 | 2,911 | -0.42% | 82 | 35 | Township |
| Hanover | 9 | 2,220 | 2,222 | 0.5% | 82 | 27 | Township |
| Madison | 10 | 2,126 | 2,129 | 0.14% | 83 | 26 | Township |
| Madison | 11 | 1,790 | 1,788 | -0.06% | 34 | 52 | Township |
| Madison | 12 | 1,747 | 1,661 | 0.98% | 48 | 37 | Township |
| Republican | 13 | 1,625 | 1,629 | 0.06% | 59 | 27 | Township |
| Graham | 14 | 1,562 | 1,583 | -0.13% | 37 | 42 | Township |
| Lancaster | 15 | 1,459 | 1,480 | -0.27% | 45 | 32 | Township |
| Saluda | 16 | 1,386 | 1,367 | 0.29% | 37 | 37 | Township |
| Madison | 17 | 1,284 | 1,281 | 0.31% | 29 | 45 | Township |
| Madison | 18 | 1,191 | 1,162 | 0.25% | 33 | 36 | Township |
| Madison | 19 | 1,135 | 1,074 | 0.89% | 32 | 35 | Township |
| Smyrna | 20 | 1,081 | 1,094 | -0.09% | 42 | 26 | Township |
| Madison | 21 | 678 | 658 | 1.04% | 26 | 26 | Township |
| Madison | 22 | 644 | 634 | 0.63% | 21 | 31 | Township |
| Madison | 23 | 467 | 448 | 1.08% | 22 | 21 | Township |
| Madison | 24 | 355 | 362 | 0% | 16 | 22 | Township |
| Dupont | 25 | 336 | 341 | -0.3% | 333 | 1 | Town |
| Brooksburg | 26 | 69 | 72 | 0% | 676 | 0 | Town |
Hanover is the largest city in Jefferson County, with a population of 21,661.
Brooksburg is the smallest city in Jefferson County, with a population of 69.
There are 26 cities in Jefferson County, Indiana.