7 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Joppatowne | Baltimore County | 13,517 |
| Jessup | Howard County | 9,456 |
| Jefferson | Frederick County | 3,011 |
| Jarrettsville | Harford County | 2,585 |
| Jugtown | Washington County | 76 |
| Jesterville | Wicomico County | 75 |
| Jennings | Garrett County | 2 |