19 cities
| City | County | 2026 Pop. ↓ |
|---|---|---|
| Lowell | Middlesex County | 122,948 |
| Lynn | Essex County | 106,731 |
| Lawrence | Essex County | 90,498 |
| Leominster | Worcester County | 44,811 |
| Lexington | Middlesex County | 35,637 |
| Ludlow | Hampden County | 21,538 |
| Longmeadow | Hampden County | 15,796 |
| Lynnfield | Essex County | 13,464 |
| Lakeville | Plymouth County | 12,570 |
| Lunenburg | Worcester County | 12,167 |
| Leicester | Worcester County | 11,402 |
| Littleton | Middlesex County | 10,773 |
| Lancaster | Worcester County | 9,279 |
| Lincoln | Middlesex County | 7,098 |
| Lee | Berkshire County | 5,644 |
| Lenox | Berkshire County | 5,072 |
| Lanesborough | Berkshire County | 2,994 |
| Leverett | Franklin County | 1,859 |
| Leyden | Franklin County | 741 |