7 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Urbana | Champaign County | 40,072 |
| University Park | Will County | 7,021 |
| Union | McHenry County | 725 |
| Ursa | Adams County | 583 |
| Ullin | Pulaski County | 455 |
| Unity | Alexander County | 68 |
| Union Hill | Kankakee County | 51 |