52 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Springfield | 1 | 112,592 | 114,375 | -0.32% | 1,838 | 61 | City |
| Capital | 2 | 111,089 | 112,543 | -0.05% | 1,868 | 59 | Township |
| Chatham | 3 | 14,695 | 14,415 | 0.38% | 1,984 | 7 | Village |
| Woodside | 4 | 11,303 | 11,538 | -0.15% | 928 | 12 | Township |
| Chatham | 5 | 8,562 | 8,412 | 0.4% | 230 | 37 | Township |
| Clear Lake | 6 | 8,278 | 8,374 | 0.01% | 246 | 34 | Township |
| Ball | 7 | 7,638 | 7,531 | 0.37% | 256 | 30 | Township |
| Fancy Creek | 8 | 5,830 | 5,870 | 0.28% | 124 | 47 | Township |
| Auburn | 9 | 5,808 | 5,936 | -0.15% | 162 | 36 | Township |
| Rochester | 10 | 5,794 | 5,513 | 2.19% | 174 | 33 | Township |
| Springfield | 11 | 5,486 | 5,573 | -0.05% | 399 | 14 | Township |
| Sherman | 12 | 4,624 | 4,671 | -0.22% | 1,472 | 3 | Village |
| Auburn | 13 | 4,429 | 4,546 | -0.54% | 1,074 | 4 | City |
| Rochester | 14 | 4,089 | 3,864 | 1.11% | 1,545 | 3 | Village |
| Riverton | 15 | 3,474 | 3,547 | -0.43% | 1,103 | 3 | Village |
| Williams | 16 | 3,431 | 3,450 | 0.15% | 80 | 43 | Township |
| Pawnee | 17 | 2,973 | 2,969 | -0.2% | 110 | 27 | Township |
| Pawnee | 18 | 2,701 | 2,683 | 0.11% | 2,028 | 1 | Village |
| Buffalo | 19 | 2,602 | 2,670 | -0.72% | 77 | 34 | Township |
| Mechanicsburg | 20 | 2,238 | 2,256 | 0.13% | 61 | 36 | Township |
| Jerome | 21 | 1,636 | 1,686 | -0.61% | 3,541 | 0 | Village |
| New Berlin | 22 | 1,560 | 1,579 | 0.26% | 50 | 31 | Township |
| Southern View | 23 | 1,541 | 1,589 | -0.64% | 2,300 | 1 | Village |
| Curran | 24 | 1,532 | 1,557 | -0.13% | 55 | 28 | Township |
| Cartwright | 25 | 1,503 | 1,506 | 0.33% | 21 | 72 | Township |
| Williamsville | 26 | 1,441 | 1,440 | 0% | 931 | 2 | Village |
| Divernon | 27 | 1,404 | 1,435 | -0.14% | 52 | 27 | Township |
| Leland Grove | 28 | 1,399 | 1,446 | -0.71% | 2,228 | 1 | City |
| Grandview | 29 | 1,381 | 1,411 | -0.43% | 4,122 | 0 | Village |
| New Berlin | 30 | 1,354 | 1,378 | -0.37% | 1,198 | 1 | Village |
| Illiopolis | 31 | 1,206 | 1,215 | 0.17% | 35 | 34 | Township |
| Divernon | 32 | 1,110 | 1,140 | -0.54% | 1,455 | 1 | Village |
| Loami | 33 | 1,105 | 1,123 | -0.09% | 52 | 21 | Township |
| Cotton Hill | 34 | 972 | 987 | -0.1% | 33 | 30 | Township |
| Cooper | 35 | 865 | 879 | -0.12% | 30 | 29 | Township |
| Illiopolis | 36 | 831 | 844 | -0.36% | 1,227 | 1 | Village |
| Pleasant Plains | 37 | 814 | 809 | 0.12% | 610 | 1 | Village |
| Loami | 38 | 794 | 809 | -0.38% | 785 | 1 | Village |
| Spaulding | 39 | 788 | 797 | -0.25% | 1,051 | 1 | Village |
| Mechanicsburg | 40 | 662 | 661 | 0% | 639 | 1 | Village |
| Thayer | 41 | 612 | 631 | -0.65% | 1,003 | 1 | Village |
| Island Grove | 42 | 564 | 572 | 0% | 20 | 28 | Township |
| Dawson | 43 | 553 | 556 | 0% | 15 | 37 | Township |
| Dawson | 44 | 509 | 517 | -0.39% | 643 | 1 | Village |
| Sherman | 45 | 466 | 488 | -0.43% | 13 | 36 | Township |
| Buffalo | 46 | 433 | 446 | -0.69% | 1,255 | 0 | Village |
| Auburn | 47 | 227 | 234 | -0.87% | 14 | 16 | Township |
| Maxwell | 48 | 210 | 214 | 0% | 10 | 21 | Township |
| Lanesville | 49 | 208 | 212 | 0% | 6 | 36 | Township |
| Buffalo Hart | 50 | 171 | 174 | 0% | 8 | 23 | Township |
| Talkington | 51 | 161 | 164 | 0% | 4 | 38 | Township |
| Cantrall | 52 | 138 | 142 | -0.72% | 552 | 0 | Village |
Springfield is the largest city in Sangamon County, with a population of 112,592.
Cantrall is the smallest city in Sangamon County, with a population of 138.
There are 52 cities in Sangamon County, Illinois.