10 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| University City | St. Louis County | 33,492 |
| Union | Franklin County | 13,404 |
| Unionville | Putnam County | 1,695 |
| Urich | Henry County | 477 |
| Urbana | Dallas County | 411 |
| Union Star | DeKalb County | 376 |
| Uplands Park | St. Louis County | 299 |
| Utica | Livingston County | 216 |
| Unity Village | Jackson County | 61 |
| Umber View Heights | Cedar County | 40 |