52 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Springfield | 1 | 111,374 | 114,298 | -0.52% | 1,818 | 61.26 | City |
| Capital township | 2 | 109,686 | 112,451 | -0.47% | 1,845 | 59.46 | Township |
| Chatham | 3 | 14,597 | 14,416 | 0.25% | 1,971 | 7.41 | Village |
| Woodside township | 4 | 11,192 | 11,549 | -0.53% | 919 | 12.18 | Township |
| Chatham township | 5 | 8,552 | 8,412 | 0.51% | 230 | 37.24 | Township |
| Clear Lake township | 6 | 8,207 | 8,373 | -0.28% | 244 | 33.69 | Township |
| Ball township | 7 | 7,621 | 7,534 | 0.41% | 256 | 29.80 | Township |
| Fancy Creek township | 8 | 5,739 | 5,866 | -0.35% | 122 | 47 | Township |
| Auburn township | 9 | 5,738 | 5,936 | -0.59% | 160 | 35.80 | Township |
| Rochester township | 10 | 5,611 | 5,507 | 0.81% | 168 | 33.37 | Township |
| Springfield township | 11 | 5,409 | 5,579 | -0.55% | 393 | 13.75 | Township |
| Sherman | 12 | 4,553 | 4,668 | -0.5% | 1,449 | 3.14 | Village |
| Auburn | 13 | 4,376 | 4,545 | -0.77% | 1,061 | 4.12 | City |
| Rochester | 14 | 3,926 | 3,858 | 0.36% | 1,484 | 2.65 | Village |
| Riverton | 15 | 3,437 | 3,531 | -0.55% | 1,091 | 3.15 | Village |
| Williams township | 16 | 3,392 | 3,447 | -0.24% | 79 | 42.78 | Township |
| Pawnee township | 17 | 2,957 | 2,969 | -0.3% | 109 | 27.09 | Township |
| Pawnee | 18 | 2,704 | 2,684 | 0.15% | 2,030 | 1.33 | Village |
| Buffalo township | 19 | 2,629 | 2,671 | -0.19% | 78 | 33.69 | Township |
| Mechanicsburg township | 20 | 2,206 | 2,254 | -0.32% | 61 | 36.42 | Township |
| Jerome | 21 | 1,616 | 1,686 | -0.86% | 3,498 | 0.46 | Village |
| New Berlin township | 22 | 1,531 | 1,580 | -0.58% | 49 | 31.24 | Township |
| Southern View | 23 | 1,526 | 1,590 | -0.84% | 2,278 | 0.67 | Village |
| Curran township | 24 | 1,522 | 1,554 | -0.33% | 55 | 27.66 | Township |
| Cartwright township | 25 | 1,484 | 1,507 | -0.2% | 21 | 71.98 | Township |
| Williamsville | 26 | 1,425 | 1,437 | -0.14% | 921 | 1.55 | Village |
| Leland Grove | 27 | 1,388 | 1,450 | -0.86% | 2,210 | 0.63 | City |
| Divernon township | 28 | 1,387 | 1,437 | -0.64% | 51 | 27.23 | Township |
| Grandview | 29 | 1,354 | 1,404 | -0.73% | 4,042 | 0.34 | Village |
| New Berlin | 30 | 1,334 | 1,379 | -0.67% | 1,181 | 1.13 | Village |
| Illiopolis township | 31 | 1,179 | 1,215 | -0.76% | 35 | 33.98 | Township |
| Loami township | 32 | 1,097 | 1,123 | -0.36% | 52 | 21.11 | Township |
| Divernon | 33 | 1,096 | 1,141 | -0.81% | 1,436 | 0.76 | Village |
| Cotton Hill township | 34 | 963 | 990 | -0.52% | 32 | 29.86 | Township |
| Cooper township | 35 | 863 | 880 | -0.23% | 30 | 28.54 | Township |
| Illiopolis | 36 | 822 | 844 | -0.48% | 1,214 | 0.68 | Village |
| Pleasant Plains | 37 | 800 | 809 | -0.25% | 599 | 1.33 | Village |
| Loami | 38 | 789 | 809 | -0.5% | 780 | 1.01 | Village |
| Spaulding | 39 | 774 | 798 | -0.64% | 1,032 | 0.75 | Village |
| Mechanicsburg | 40 | 656 | 661 | -0.15% | 633 | 1.04 | Village |
| Thayer | 41 | 604 | 631 | -0.82% | 990 | 0.61 | Village |
| Island Grove township | 42 | 560 | 573 | -0.36% | 20 | 28.07 | Township |
| Dawson township | 43 | 542 | 555 | -0.73% | 15 | 37.33 | Township |
| Dawson | 44 | 500 | 517 | -0.6% | 631 | 0.79 | Village |
| Sherman township | 45 | 455 | 488 | -1.3% | 13 | 36.02 | Township |
| Buffalo | 46 | 427 | 446 | -0.93% | 1,238 | 0.34 | Village |
| Auburn township | 47 | 226 | 235 | -0.44% | 14 | 15.81 | Township |
| Lanesville township | 48 | 208 | 212 | 0% | 6 | 36.22 | Township |
| Maxwell township | 49 | 206 | 213 | -0.48% | 10 | 21.03 | Township |
| Buffalo Hart township | 50 | 168 | 174 | -0.59% | 7 | 22.69 | Township |
| Talkington township | 51 | 160 | 163 | 0% | 4 | 37.51 | Township |
| Cantrall | 52 | 136 | 141 | -0.73% | 544 | 0.25 | Village |
Springfield is the largest city in Sangamon County, with a population of 111,374.
Cantrall is the smallest city in Sangamon County.
There are 52 cities in Sangamon County, Illinois.