52 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Springfield | 1 | 112,236 | 114,375 | -0.32% | 1,832 | 61 | City |
| Capital | 2 | 111,038 | 112,543 | -0.05% | 1,867 | 59 | Township |
| Chatham | 3 | 14,751 | 14,415 | 0.38% | 1,992 | 7 | Village |
| Woodside | 4 | 11,286 | 11,538 | -0.15% | 926 | 12 | Township |
| Chatham | 5 | 8,596 | 8,412 | 0.4% | 231 | 37 | Township |
| Clear Lake | 6 | 8,279 | 8,374 | 0.01% | 246 | 34 | Township |
| Ball | 7 | 7,666 | 7,531 | 0.37% | 257 | 30 | Township |
| Rochester | 8 | 5,918 | 5,513 | 2.14% | 177 | 33 | Township |
| Fancy Creek | 9 | 5,846 | 5,870 | 0.27% | 124 | 47 | Township |
| Auburn | 10 | 5,799 | 5,936 | -0.15% | 162 | 36 | Township |
| Springfield | 11 | 5,483 | 5,573 | -0.05% | 399 | 14 | Township |
| Sherman | 12 | 4,615 | 4,671 | -0.19% | 1,469 | 3 | Village |
| Auburn | 13 | 4,406 | 4,546 | -0.52% | 1,068 | 4 | City |
| Rochester | 14 | 4,134 | 3,864 | 1.1% | 1,541 | 3 | Village |
| Riverton | 15 | 3,460 | 3,547 | -0.4% | 1,098 | 3 | Village |
| Williams | 16 | 3,436 | 3,450 | 0.15% | 80 | 43 | Township |
| Pawnee | 17 | 2,967 | 2,969 | -0.2% | 110 | 27 | Township |
| Pawnee | 18 | 2,705 | 2,683 | 0.15% | 2,031 | 1 | Village |
| Buffalo | 19 | 2,583 | 2,670 | -0.73% | 77 | 34 | Township |
| Mechanicsburg | 20 | 2,241 | 2,256 | 0.13% | 62 | 36 | Township |
| Jerome | 21 | 1,626 | 1,686 | -0.61% | 3,519 | 0 | Village |
| New Berlin | 22 | 1,564 | 1,579 | 0.26% | 50 | 31 | Township |
| Southern View | 23 | 1,532 | 1,589 | -0.58% | 2,287 | 1 | Village |
| Curran | 24 | 1,530 | 1,557 | -0.13% | 55 | 28 | Township |
| Cartwright | 25 | 1,508 | 1,506 | 0.33% | 21 | 72 | Township |
| Williamsville | 26 | 1,441 | 1,440 | 0% | 931 | 2 | Village |
| Divernon | 27 | 1,402 | 1,435 | -0.14% | 51 | 27 | Township |
| Leland Grove | 28 | 1,390 | 1,446 | -0.64% | 2,213 | 1 | City |
| Grandview | 29 | 1,375 | 1,411 | -0.43% | 4,104 | 0 | Village |
| New Berlin | 30 | 1,349 | 1,378 | -0.37% | 1,194 | 1 | Village |
| Illiopolis | 31 | 1,208 | 1,215 | 0.17% | 36 | 34 | Township |
| Loami | 32 | 1,104 | 1,123 | -0.09% | 52 | 21 | Township |
| Divernon | 33 | 1,104 | 1,140 | -0.54% | 1,447 | 1 | Village |
| Cotton Hill | 34 | 971 | 987 | -0.1% | 33 | 30 | Township |
| Cooper | 35 | 864 | 879 | -0.12% | 30 | 29 | Township |
| Illiopolis | 36 | 829 | 844 | -0.24% | 1,225 | 1 | Village |
| Pleasant Plains | 37 | 815 | 809 | 0.12% | 610 | 1 | Village |
| Loami | 38 | 791 | 809 | -0.38% | 782 | 1 | Village |
| Spaulding | 39 | 786 | 797 | -0.25% | 1,048 | 1 | Village |
| Mechanicsburg | 40 | 662 | 661 | 0% | 639 | 1 | Village |
| Thayer | 41 | 608 | 631 | -0.65% | 997 | 1 | Village |
| Island Grove | 42 | 564 | 572 | 0% | 20 | 28 | Township |
| Dawson | 43 | 553 | 556 | 0% | 15 | 37 | Township |
| Dawson | 44 | 508 | 517 | -0.2% | 641 | 1 | Village |
| Sherman | 45 | 464 | 488 | -0.43% | 13 | 36 | Township |
| Buffalo | 46 | 431 | 446 | -0.46% | 1,249 | 0 | Village |
| Auburn | 47 | 225 | 234 | -0.88% | 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 | 137 | 142 | -0.72% | 548 | 0 | Village |
Springfield is the largest city in Sangamon County, with a population of 112,236.
Cantrall is the smallest city in Sangamon County, with a population of 137.
There are 52 cities in Sangamon County, Illinois.