Germantown is an urbanized census-designated place (CDP) in Montgomery County, Maryland in the United States. It is the sixth most populous CDP in Maryland with an estimated population of 85,000 as of 2005. If it were to incorporate along CDP boundaries, it would become the second largest incorporated city in Maryland. . It is located approximately 20 miles outside of Washington DC and part of the Washington Metropolitan Area Germantown has the assigned ZIP Codes of 20874 and 20876 for delivery and 20875 for post office boxes. It is the only "Germantown, Maryland" recognized by the United States Postal Service, even though there are technically three others, one in Anne Arundel County, one in Baltimore County, and one in Worcester County.