| Localité | Code postal |
|---|---|
| Abell, St. Mary's | 20606 |
| Avenue, St. Mary's | 20609 |
| Beachville, St. Mary's | 20684 |
| Bushwood, St. Mary's | 20618 |
| California, St. Mary's | 20619 |
| Callaway, St. Mary's | 20620 |
| Chaptico, St. Mary's | 20621 |
| Charlotte Hall, St. Mary's | 20622 |
| Clements, St. Mary's | 20624 |
| Coltons Point, St. Mary's | 20626 |
| Compton, St. Mary's | 20627 |
| Dameron, St. Mary's | 20628 |
| Drayden, St. Mary's | 20630 |
| Great Mills, St. Mary's | 20634 |
| Helen, St. Mary's | 20635 |
| Hollywood, St. Mary's | 20636 |
| Leonardtown, St. Mary's | 20650 |
| Lexington Park, St. Mary's | 20653 |
| Loveville, St. Mary's | 20656 |
| Maddox, St. Mary's | 20621 |
| Mechanicsville, St. Mary's | 20659 |
| Morganza, St. Mary's | 20660 |
| Park Hall, St. Mary's | 20667 |
| Patuxent River, St. Mary's | 20670 |
| Piney Point, St. Mary's | 20674 |
| Ridge, St. Mary's | 20680 |