26 ZIP Codes
| Zip Code | City | Population ↓ |
|---|---|---|
| 20653 | Lexington Park | 26,852 |
| 20659 | Mechanicsville | 24,324 |
| 20650 | Leonardtown | 16,094 |
| 20619 | California | 14,212 |
| 20636 | Hollywood | 10,486 |
| 20634 | Great Mills | 7,088 |
| 20670 | Patuxent River | 2,046 |
| 20618 | Bushwood | 1,705 |
| 20620 | Callaway | 1,115 |
| 20690 | Tall Timbers | 1,077 |
| 20686 | Saint Marys City | 971 |
| 20621 | Chaptico | 958 |
| 20684 | Saint Inigoes | 802 |
| 20624 | Clements | 796 |
| 20674 | Piney Point | 769 |
| 20609 | Avenue | 714 |
| 20680 | Ridge | 663 |
| 20630 | Drayden | 559 |
| 20692 | Valley Lee | 505 |
| 20628 | Dameron | 503 |
| 20687 | Scotland | 415 |
| 20606 | Abell | 291 |
| 20626 | Coltons Point | 284 |
| 20667 | Park Hall | 150 |
| 20656 | Loveville | 87 |
| 20660 | Morganza | 14 |
The data shown reflect ZCTAs from the US Census. As of 2025, there are 26 ZCTAs in St. Mary's County, Maryland (US Census).