| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Waukegan | 1 | 87,705 | 89,128 | -0.27% | 3,622 | 24 | City |
| Buffalo Grove | 2 | 42,768 | 43,083 | -0.1% | 4,474 | 10 | Village |
| North Chicago | 3 | 34,886 | 30,742 | 2.46% | 4,363 | 8 | City |
| Mundelein | 4 | 32,915 | 31,544 | 0.72% | 3,009 | 11 | Village |
| Highland Park | 5 | 30,889 | 30,159 | 0.4% | 2,525 | 12 | City |
| Gurnee | 6 | 30,395 | 30,650 | -0.21% | 2,249 | 14 | Village |
| McHenry | 7 | 29,580 | 27,383 | 1.24% | 1,967 | 15 | City |
| Lake in the Hills | 8 | 28,530 | 28,927 | -0.21% | 2,788 | 10 | Village |
| Round Lake Beach | 9 | 26,839 | 27,208 | -0.23% | 5,321 | 5 | Village |
| Vernon Hills | 10 | 26,838 | 26,815 | 0.05% | 3,469 | 8 | Village |
| Zion | 11 | 24,376 | 24,724 | -0.29% | 2,455 | 10 | City |
| Grayslake | 12 | 21,126 | 21,224 | -0.07% | 1,936 | 11 | Village |
| Libertyville | 13 | 20,697 | 20,561 | -0.02% | 2,350 | 9 | Village |
| Lake Zurich | 14 | 19,887 | 19,788 | 0.1% | 2,873 | 7 | Village |
| Lake Forest | 15 | 19,831 | 19,350 | 0.51% | 1,153 | 17 | City |
| Deerfield | 16 | 19,625 | 19,129 | -0.09% | 3,543 | 6 | Village |
| Round Lake | 17 | 18,491 | 18,689 | -0.19% | 3,326 | 6 | Village |
| Antioch | 18 | 15,105 | 14,610 | 0.7% | 1,833 | 8 | Village |
| Lindenhurst | 19 | 14,838 | 14,376 | 0.19% | 3,278 | 5 | Village |
| Beach Park | 20 | 14,089 | 14,228 | -0.18% | 1,991 | 7 | Village |
| Wauconda | 21 | 13,972 | 14,067 | -0.15% | 2,755 | 5 | Village |
| Fox Lake | 22 | 10,828 | 10,962 | -0.19% | 1,382 | 8 | Village |
| Barrington | 23 | 10,558 | 10,709 | -0.26% | 2,287 | 5 | Village |
| Hawthorn Woods | 24 | 9,789 | 9,106 | 1.14% | 1,203 | 8 | Village |
| Lake Villa | 25 | 8,684 | 8,728 | -0.09% | 1,329 | 7 | Village |
| Long Grove | 26 | 8,335 | 8,381 | -0.1% | 673 | 12 | Village |
| Island Lake | 27 | 8,048 | 8,042 | 0.01% | 2,403 | 3 | Village |
| Lincolnshire | 28 | 7,972 | 7,942 | 0.11% | 1,748 | 5 | Village |
| Park City | 29 | 7,896 | 7,877 | 0.04% | 6,825 | 1 | City |
| Round Lake Park | 30 | 7,881 | 7,664 | 0.47% | 3,818 | 2 | Village |
| Volo | 31 | 6,981 | 6,190 | 2.59% | 1,693 | 4 | Village |
| Winthrop Harbor | 32 | 6,513 | 6,579 | -0.18% | 1,405 | 5 | Village |
| Lakemoor | 33 | 6,511 | 6,172 | 0.96% | 1,228 | 5 | Village |
| Johnsburg | 34 | 6,458 | 6,376 | 0.2% | 890 | 7 | Village |
| Lake Bluff | 35 | 5,553 | 5,609 | -0.18% | 1,362 | 4 | Village |
| Highwood | 36 | 5,386 | 5,088 | 1.18% | 7,481 | 1 | City |
| Kildeer | 37 | 4,796 | 4,086 | 2.41% | 1,112 | 4 | Village |
| Green Oaks | 38 | 4,075 | 4,112 | -0.17% | 1,021 | 4 | Village |
| Hainesville | 39 | 3,493 | 3,541 | -0.23% | 1,891 | 2 | Village |
| Wadsworth | 40 | 3,483 | 3,508 | -0.14% | 354 | 10 | Village |
| Round Lake Heights | 41 | 2,573 | 2,614 | -0.27% | 4,475 | 1 | Village |
| Oakwood Hills | 42 | 2,043 | 2,071 | -0.15% | 1,878 | 1 | Village |
| Third Lake | 43 | 1,100 | 1,115 | -0.27% | 1,871 | 1 | Village |
| McCullom Lake | 44 | 958 | 981 | -0.42% | 2,761 | 0 | Village |
| Holiday Hills | 45 | 604 | 617 | -0.33% | 647 | 1 | Village |
| Mettawa | 46 | 573 | 533 | 1.06% | 105 | 5 | Village |
| Indian Creek | 47 | 530 | 533 | -0.19% | 1,985 | 0 | Village |
| Trout Valley | 48 | 509 | 514 | -0.2% | 1,189 | 0 | Village |
| Old Mill Creek | 49 | 161 | 165 | -0.62% | 15 | 11 | Village |
Waukegan is the largest city in Lake County, with a population of 87,705.
Old Mill Creek is the smallest city in Lake County, with a population of 161.
There are 49 cities in Lake County, Illinois.