64 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rutland township | 1 | 28,377 | 26,776 | 0.93% | 785 | 36.15 | Township |
| Ottawa | 2 | 18,691 | 18,843 | -0.16% | 1,255 | 14.89 | City |
| LaSalle township | 3 | 13,202 | 13,400 | -0.02% | 783 | 16.86 | Township |
| Streator | 4 | 12,135 | 12,470 | -0.55% | 1,659 | 7.32 | City |
| Bruce township | 5 | 11,715 | 11,919 | -0.08% | 690 | 16.98 | Township |
| Ottawa township | 6 | 11,256 | 11,252 | 0.33% | 741 | 15.18 | Township |
| Peru township | 7 | 10,010 | 10,152 | -0.01% | 573 | 17.48 | Township |
| Peru | 8 | 9,686 | 9,921 | -0.48% | 934 | 10.37 | City |
| LaSalle | 9 | 9,344 | 9,563 | -0.47% | 694 | 13.46 | City |
| South Ottawa township | 10 | 8,373 | 8,350 | 0.36% | 426 | 19.66 | Township |
| Northville township | 11 | 7,328 | 7,337 | 0.21% | 224 | 32.70 | Township |
| Mendota township | 12 | 7,035 | 7,153 | -0.06% | 196 | 35.93 | Township |
| Mendota | 13 | 6,856 | 7,038 | -0.52% | 1,337 | 5.13 | City |
| Marseilles | 14 | 4,741 | 4,820 | -0.34% | 524 | 9.05 | City |
| Mission township | 15 | 4,068 | 4,073 | 0.2% | 128 | 31.68 | Township |
| Oglesby | 16 | 3,599 | 3,699 | -0.55% | 721 | 4.99 | City |
| Rutland township | 17 | 3,572 | 3,592 | 0.17% | 102 | 34.99 | Township |
| Seneca township | 18 | 2,876 | 2,890 | 0% | 80 | 35.87 | Township |
| Otter Creek township | 19 | 2,643 | 2,663 | 0.11% | 74 | 35.81 | Township |
| Earl township | 20 | 2,437 | 2,454 | 0.08% | 65 | 37.48 | Township |
| Dayton township | 21 | 2,432 | 2,419 | 0.37% | 115 | 21.09 | Township |
| Sheridan | 22 | 2,408 | 2,432 | -0.21% | 1,135 | 2.12 | Village |
| Seneca | 23 | 2,289 | 2,343 | -0.48% | 369 | 6.21 | Village |
| Utica township | 24 | 1,956 | 1,933 | 0.36% | 109 | 18.01 | Township |
| Adams township | 25 | 1,593 | 1,620 | -0.13% | 48 | 33.11 | Township |
| Earlville | 26 | 1,587 | 1,611 | -0.31% | 1,321 | 1.20 | City |
| Eagle township | 27 | 1,441 | 1,465 | -0.07% | 46 | 31.27 | Township |
| Eden township | 28 | 1,353 | 1,379 | -0.15% | 37 | 36.17 | Township |
| North Utica | 29 | 1,342 | 1,317 | 0.37% | 388 | 3.46 | Village |
| Troy Grove township | 30 | 1,268 | 1,278 | 0.08% | 36 | 35.67 | Township |
| Serena township | 31 | 1,113 | 1,121 | 0.09% | 30 | 37.17 | Township |
| Leland | 32 | 919 | 946 | -0.54% | 1,721 | 0.53 | Village |
| Farm Ridge township | 33 | 838 | 839 | 0.48% | 24 | 34.78 | Township |
| Fall River township | 34 | 792 | 790 | 0.38% | 39 | 20.19 | Township |
| Dimmick township | 35 | 740 | 746 | 0% | 20 | 36.54 | Township |
| Tonica | 36 | 726 | 748 | -0.55% | 533 | 1.36 | Village |
| Freedom township | 37 | 603 | 608 | 0.17% | 16 | 37.36 | Township |
| Miller township | 38 | 585 | 587 | 0.17% | 17 | 35.19 | Township |
| Hope township | 39 | 581 | 580 | 0.35% | 16 | 36.36 | Township |
| Wallace township | 40 | 571 | 573 | 0.18% | 21 | 27.58 | Township |
| Grand Ridge | 41 | 506 | 516 | -0.39% | 1,095 | 0.46 | Village |
| Allen township | 42 | 504 | 506 | 0.4% | 14 | 36.23 | Township |
| Dayton | 43 | 488 | 475 | -0.81% | 265 | 1.84 | CDP |
| Deer Park township | 44 | 474 | 475 | 0.21% | 15 | 31.33 | Township |
| Sheridan township | 45 | 447 | 462 | -0.89% | 13 | 35.51 | Township |
| Ophir township | 46 | 437 | 440 | 0% | 13 | 34.95 | Township |
| Lostant | 47 | 431 | 433 | 0% | 381 | 1.13 | Village |
| Waltham township | 48 | 415 | 419 | 0% | 12 | 36.03 | Township |
| Naplate | 49 | 409 | 418 | -0.49% | 2,509 | 0.16 | Village |
| Vermillion township | 50 | 377 | 381 | 0% | 16 | 23.05 | Township |
| Richland township | 51 | 342 | 346 | 0% | 14 | 24.27 | Township |
| Ransom | 52 | 305 | 310 | -0.33% | 305 | 1 | Village |
| Grand Rapids township | 53 | 277 | 280 | 0% | 8 | 35.60 | Township |
| Meriden township | 54 | 265 | 266 | 0% | 8 | 35.28 | Township |
| Cedar Point | 55 | 258 | 267 | -0.77% | 253 | 1.02 | Village |
| Serena | 56 | 258 | 137 | 7.5% | 1,049 | 0.25 | CDP |
| Rutland | 57 | 254 | 256 | 0% | 366 | 0.69 | Village |
| Osage township | 58 | 246 | 246 | 0% | 6 | 38.29 | Township |
| Kangley | 59 | 226 | 233 | -0.44% | 866 | 0.26 | Village |
| Troy Grove | 60 | 219 | 223 | -0.45% | 319 | 0.69 | Village |
| Wedron | 61 | 181 | 170 | 7.1% | 349 | 0.52 | CDP |
| Dana | 62 | 155 | 159 | -0.64% | 705 | 0.22 | Village |
| Leonore | 63 | 119 | 123 | -0.83% | 1,337 | 0.09 | Village |
| Triumph | 64 | 106 | 82 | 7.07% | 711 | 0.15 | CDP |
Rutland township is the largest city in LaSalle County, with a population of 28,377.
Triumph is the smallest city in LaSalle County.
There are 64 cities in LaSalle County, Illinois.