6 cities
| City | County | 2026 Pop. ↓ |
|---|---|---|
| Joppatowne | Baltimore County | 13,577 |
| Jessup | Howard County | 9,611 |
| Jefferson | Frederick County | 3,071 |
| Jarrettsville | Harford County | 2,563 |
| Jesterville | Wicomico County | 67 |
| Jugtown | Washington County | 67 |