6 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Joppatowne | Baltimore County | 13,585 |
| Jessup | Howard County | 10,218 |
| Jefferson | Frederick County | 2,900 |
| Jarrettsville | Harford County | 2,617 |
| Jugtown | Washington County | 127 |
| Jesterville | Wicomico County | 43 |