26 zips
| Zip Code | City | Population ↓ |
|---|---|---|
| 20653 | Lexington Park | 26,799 |
| 20659 | Mechanicsville | 23,918 |
| 20650 | Leonardtown | 15,979 |
| 20619 | California | 14,743 |
| 20636 | Hollywood | 10,357 |
| 20634 | Great Mills | 6,976 |
| 20670 | Patuxent River | 1,577 |
| 20618 | Bushwood | 1,513 |
| 20620 | Callaway | 1,160 |
| 20624 | Clements | 1,157 |
| 20690 | Tall Timbers | 1,046 |
| 20609 | Avenue | 976 |
| 20686 | Saint Marys City | 949 |
| 20621 | Chaptico | 902 |
| 20684 | Saint Inigoes | 825 |
| 20628 | Dameron | 791 |
| 20680 | Ridge | 702 |
| 20674 | Piney Point | 638 |
| 20692 | Valley Lee | 438 |
| 20630 | Drayden | 346 |
| 20687 | Scotland | 331 |
| 20606 | Abell | 204 |
| 20626 | Coltons Point | 198 |
| 20656 | Loveville | 122 |
| 20667 | Park Hall | 98 |
| 20660 | Morganza | 16 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 26 ZCTAs in St. Mary's County, Maryland (US Census).