Great Mills, Maryland Area Code

Great Mills, MD is officially utilizing an area code overlay in which area codes 240 and 301 serve the same geographic area. Ten digit dialing (area code + seven digit number) is necessary.

In addition to Great Mills, MD area code information read more about area codes 240 and 301 details and Maryland area codes.

Great Mills, MD is located in Saint Marys County and observes the Eastern Time Zone. View our Times by Area Code tool.