23 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 |
| Chatham | 2 | 14,597 | 14,416 | 0.25% | 1,971 | 7.41 | Village |
| Sherman | 3 | 4,553 | 4,668 | -0.5% | 1,449 | 3.14 | Village |
| Auburn | 4 | 4,376 | 4,545 | -0.77% | 1,061 | 4.12 | City |
| Rochester | 5 | 3,926 | 3,858 | 0.36% | 1,484 | 2.65 | Village |
| Riverton | 6 | 3,437 | 3,531 | -0.55% | 1,091 | 3.15 | Village |
| Pawnee | 7 | 2,704 | 2,684 | 0.15% | 2,030 | 1.33 | Village |
| Jerome | 8 | 1,616 | 1,686 | -0.86% | 3,498 | 0.46 | Village |
| Southern View | 9 | 1,526 | 1,590 | -0.84% | 2,278 | 0.67 | Village |
| Williamsville | 10 | 1,425 | 1,437 | -0.14% | 921 | 1.55 | Village |
| Leland Grove | 11 | 1,388 | 1,450 | -0.86% | 2,210 | 0.63 | City |
| Grandview | 12 | 1,354 | 1,404 | -0.73% | 4,042 | 0.34 | Village |
| New Berlin | 13 | 1,334 | 1,379 | -0.67% | 1,181 | 1.13 | Village |
| Divernon | 14 | 1,096 | 1,141 | -0.81% | 1,436 | 0.76 | Village |
| Illiopolis | 15 | 822 | 844 | -0.48% | 1,214 | 0.68 | Village |
| Pleasant Plains | 16 | 800 | 809 | -0.25% | 599 | 1.33 | Village |
| Loami | 17 | 789 | 809 | -0.5% | 780 | 1.01 | Village |
| Spaulding | 18 | 774 | 798 | -0.64% | 1,032 | 0.75 | Village |
| Mechanicsburg | 19 | 656 | 661 | -0.15% | 633 | 1.04 | Village |
| Thayer | 20 | 604 | 631 | -0.82% | 990 | 0.61 | Village |
| Dawson | 21 | 500 | 517 | -0.6% | 631 | 0.79 | Village |
| Buffalo | 22 | 427 | 446 | -0.93% | 1,238 | 0.34 | Village |
| Cantrall | 23 | 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 23 cities in Sangamon County, Illinois.