18 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oquawka | 1 | 1,558 | 1,658 | -0.89% | 64 | 24 | Township |
| Oquawka | 2 | 1,046 | 1,129 | -1.32% | 712 | 1 | Village |
| Stronghurst | 3 | 1,004 | 1,067 | -0.69% | 28 | 36 | Township |
| Gladstone | 4 | 761 | 811 | -0.91% | 16 | 47 | Township |
| Stronghurst | 5 | 752 | 812 | -1.31% | 861 | 1 | Village |
| Lomax | 6 | 681 | 741 | -1.45% | 24 | 28 | Township |
| Biggsville | 7 | 506 | 546 | -1.36% | 14 | 37 | Township |
| Lomax | 8 | 367 | 403 | -1.61% | 309 | 1 | Village |
| Media | 9 | 336 | 357 | -0.59% | 9 | 36 | Township |
| Biggsville | 10 | 280 | 301 | -1.06% | 831 | 0 | Village |
| Raritan | 11 | 232 | 248 | -0.85% | 7 | 34 | Township |
| Carman | 12 | 227 | 238 | -0.87% | 10 | 22 | Township |
| Rozetta | 13 | 220 | 235 | -0.9% | 6 | 36 | Township |
| Gladstone | 14 | 215 | 232 | -1.38% | 597 | 0 | Village |
| Bald Bluff | 15 | 206 | 217 | -0.96% | 5 | 42 | Township |
| Terre Haute | 16 | 203 | 217 | -0.98% | 6 | 36 | Township |
| Media | 17 | 108 | 117 | -0.92% | 64 | 2 | Village |
| Raritan | 18 | 95 | 103 | -1.04% | 1,000 | 0 | Village |
Oquawka is the largest city in Henderson County, with a population of 1,558.
Raritan is the smallest city in Henderson County, with a population of 95.
There are 18 cities in Henderson County, Illinois.