11 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Indiana | Indiana County | 14,464 |
| Indiana township | Indiana County | 7,154 |
| Irwin | Westmoreland County | 3,765 |
| Ingram | Allegheny County | 3,176 |
| Independence township | Beaver County | 2,209 |
| Industry | Beaver County | 1,764 |
| Independence township | Washington County | 1,491 |
| Irwin township | Westmoreland County | 1,212 |
| Ivyland | Bucks County | 942 |
| Irvona | Clearfield County | 526 |
| Indian Lake | Somerset County | 388 |