| Zip Code | City | Population ↓ |
|---|---|---|
| 21234 | Parkville | 66,095 |
| 21222 | Dundalk | 60,013 |
| 21117 | Owings Mills | 58,516 |
| 21207 | Gwynn Oak | 51,765 |
| 21228 | Catonsville | 50,268 |
| 21221 | Essex | 43,822 |
| 21220 | Middle River | 42,652 |
| 21244 | Windsor Mill | 39,501 |
| 21093 | Lutherville Timonium | 38,961 |
| 21236 | Nottingham | 38,632 |
| 21208 | Pikesville | 37,319 |
| 21227 | Halethorpe | 35,052 |
| 21136 | Reisterstown | 35,038 |
| 21133 | Randallstown | 32,070 |
| 21237 | Rosedale | 30,983 |
| 21209 | Baltimore | 29,960 |
| 21030 | Cockeysville | 25,133 |
| 21286 | Towson | 21,142 |
| 21204 | Towson | 20,188 |
| 21128 | Perry Hall | 15,934 |
| 21219 | Sparrows Point | 9,605 |
| 21131 | Phoenix | 7,722 |
| 21120 | Parkton | 7,319 |
| 21163 | Woodstock | 7,222 |
| 21152 | Sparks Glencoe | 6,517 |
| 21087 | Kingsville | 5,597 |
| 21013 | Baldwin | 5,382 |
| 21111 | Monkton | 4,838 |
| 21057 | Glen Arm | 4,530 |
| 21252 | Towson | 4,456 |
| 21162 | White Marsh | 4,322 |
| 21155 | Upperco | 3,063 |
| 21053 | Freeland | 3,051 |
| 21250 | Baltimore | 2,959 |
| 21082 | Hydes | 694 |
| 21153 | Stevenson | 676 |
| 21071 | Glyndon | 526 |
| 21052 | Fort Howard | 438 |
| 21156 | Upper Falls | 362 |
| 21051 | Fork | 113 |
| 21023 | Butler | 68 |
| 21105 | Maryland Line | 40 |
| 21031 | Hunt Valley | 26 |
| 21285 | Towson | 10 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 44 ZCTAs in Baltimore County, Maryland (US Census).