Post office locations in 20878
| Post Office | Address | Phone | Hours |
| DIAMOND FARMS | 23 FIRSTFIELD RD GAITHERSBURG, MD 20878 - 9998 | 301-208-3735 | Mon-Fri 09:00 AM - 05:00 PM Sat 09:00 AM - 01:00 PM Sun Closed |
| DIAMOND FARMS RURAL | 7 METROPOLITAN CT GAITHERSBURG, MD 20878 - 9906 | 301-208-3735 | |
| KENTLANDS | 618 CENTER POINT WAY GAITHERSBURG, MD 20878 - 9997 | 301-869-4866 | Mon-Fri 09:00 AM - 05:00 PM Sat 09:00 AM - 01:00 PM Sun Closed |