7 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Urbana | Champaign County | 38,196 |
| University Park | Will County | 6,917 |
| Union | McHenry County | 623 |
| Ursa | Adams County | 582 |
| Ullin | Pulaski County | 437 |
| Unity | Alexander County | 68 |
| Union Hill | Kankakee County | 52 |