List of US Post Office Stores in Upper Marlboro, MD Outlet Note Regular Brands US Post Office Maryland Upper Marlboro Rating 4.5 based on 76 votes Official Website https://www.usps.com/ Products Postal Service NameAddressPhone Name/Address/Phone US Post Office outlet - Upper Marlboro 68 Watkins Park Dr (301) 249-4036 US Post Office outlet - Upper Marlboro 14605 Elm St (301) 780-3427 US Post Office outlet - Upper Marlboro 9801 Apollo Dr (301) 925-1485 People Also Viewed