10 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| University City | St. Louis County | 34,143 |
| Union | Franklin County | 13,399 |
| Unionville | Putnam County | 1,652 |
| Urich | Henry County | 478 |
| Urbana | Dallas County | 411 |
| Union Star | DeKalb County | 376 |
| Uplands Park | St. Louis County | 302 |
| Utica | Livingston County | 222 |
| Unity Village | Jackson County | 59 |
| Umber View Heights | Cedar County | 44 |