There are 33 cities in DeKalb County, Illinois.
Note: As defined by the US Census Bureau, a city's official boundaries often extend miles beyond the city itself and may even cross county lines. As such, several thousand US cities officially exist in two or more counties (and therefore appear on multiple counties' lists of cities.)
City | Rank | 2024 Population | 2020 Population | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Elgin | 1 | 112,874 | 114,617 | -0.39% | 2,959 | 38.1 | City |
| DeKalb | 2 | 40,208 | 40,219 | -0.01% | 2,320 | 17.3 | City |
| Huntley | 3 | 28,436 | 27,766 | 0.59% | 1,941 | 14.7 | Village |
| Sycamore | 4 | 18,717 | 18,576 | 0.19% | 1,849 | 10.1 | City |
| Pingree Grove | 5 | 11,383 | 10,399 | 2.21% | 2,754 | 4.1 | Village |
| Rochelle | 6 | 9,281 | 9,432 | -0.41% | 675 | 13.8 | City |
| Sugar Grove | 7 | 9,193 | 9,259 | -0.18% | 870 | 10.6 | Village |
| Hampshire | 8 | 8,232 | 7,646 | 1.81% | 856 | 9.6 | Village |
| Marengo | 9 | 7,625 | 7,555 | 0.22% | 857 | 8.9 | City |
| Sandwich | 10 | 7,212 | 7,212 | 0% | 1,523 | 4.7 | City |
| Elburn | 11 | 6,676 | 6,208 | 1.78% | 1,780 | 3.8 | Village |
| Lake Holiday | 12 | 5,606 | 5,365 | 1.1% | 1,599 | 3.5 | CDP |
| Genoa | 13 | 5,480 | 5,307 | 0.79% | 2,111 | 2.6 | City |
| Cortland | 14 | 4,518 | 4,397 | 0.67% | 1,257 | 3.6 | Town |
| Hinckley | 15 | 1,962 | 1,997 | -0.46% | 2,289 | 0.9 | Village |
| Somonauk | 16 | 1,751 | 1,785 | -0.51% | 700 | 2.5 | Village |
| Kirkland | 17 | 1,608 | 1,648 | -0.62% | 1,295 | 1.2 | Village |
| Earlville | 18 | 1,592 | 1,611 | -0.31% | 1,326 | 1.2 | City |
| Maple Park | 19 | 1,493 | 1,432 | 1.01% | 652 | 2.3 | Village |
| Waterman | 20 | 1,417 | 1,433 | -0.28% | 946 | 1.5 | Village |
| Hillcrest | 21 | 1,210 | 1,221 | -0.25% | 341 | 3.5 | Village |
| Malta | 22 | 1,128 | 1,142 | -0.35% | 1,834 | 0.6 | Village |
| Kingston | 23 | 1,083 | 1,106 | -0.55% | 1,101 | 1.0 | Village |
| Big Rock | 24 | 1,077 | 1,105 | -0.65% | 249 | 4.3 | Village |
| Lily Lake | 25 | 1,043 | 1,035 | 0.19% | 384 | 2.7 | Village |
| Leland | 26 | 924 | 946 | -0.65% | 1,730 | 0.5 | Village |
| Shabbona | 27 | 845 | 865 | -0.59% | 659 | 1.3 | Village |
| Creston | 28 | 616 | 627 | -0.48% | 538 | 1.1 | Village |
| Burlington | 29 | 519 | 535 | -0.77% | 76 | 6.9 | Village |
| Kings | 30 | 405 | 348 | 7.71% | 2,647 | 0.2 | CDP |
| Lee | 31 | 303 | 313 | -0.98% | 1,530 | 0.2 | Village |
| Virgil | 32 | 281 | 289 | -0.71% | 129 | 2.2 | Village |
| Harding | 33 | 128 | 153 | 7.56% | 753 | 0.2 | CDP |
Note: City markers shown outside the county boundary mean that a part of the city extends into this county, but is primarily located in an adjacent county.
Elgin is the largest city in DeKalb County.
Harding is the smallest city in DeKalb County.
There are 33 cities in DeKalb County, Illinois.