Maryland ZIP codes
Maryland holds 605 ZIP codes between 20588 and 21930. The tables rank the places and counties with the most codes; the guide below decodes the numbering.
Places with the most ZIP codes in Maryland
| Place | ZIP codes |
|---|---|
| Baltimore | 42 |
| Silver Spring | 16 |
| Bethesda | 11 |
| Gaithersburg | 9 |
| Annapolis | 8 |
| Rockville | 8 |
| Laurel | 7 |
| Bowie | 7 |
| Hyattsville | 7 |
| Frederick | 6 |
| Hagerstown | 6 |
| Cumberland | 5 |
| Towson | 5 |
| Capitol Heights | 5 |
| Upper Marlboro | 5 |
| Waldorf | 4 |
| Salisbury | 4 |
| Glen Burnie | 3 |
| Ellicott City | 3 |
| Columbia | 3 |
Maryland counties by ZIP count
| County | ZIP codes |
|---|---|
| Montgomery | 76 |
| Prince George's | 64 |
| Baltimore | 53 |
| Anne Arundel | 43 |
| Baltimore (city) | 39 |
| Frederick | 31 |
| St. Mary's | 29 |
| Charles | 24 |
| Washington | 23 |
| Allegany | 22 |
Reading a Maryland ZIP code
Maryland holds 605 ZIP codes between 20588 and 21930, spread over 24 counties. Baltimore leads the state with 42 codes, ahead of Silver Spring with 16. Every code here opens with the digit 2: that opening number is the national postal region Maryland belongs to, the next two digits name the sectional center that sorts the mail, and the final two point to the local office. A ZIP+4 suffix narrows delivery to a block face. Boundaries follow carrier routes rather than city limits, which is why Baltimore spreads across 42 codes while some rural codes cross county lines.
Source: GeoNames postal dataset (CC BY 4.0), snapshot of 2026-07-09. Counts cover standard delivery ZIPs listed for Maryland; unique and PO box codes may add to these totals.
Last updated: · Methodology and sources