The post office located at the intersection of Main Street Extension and Leyden Street was the main post office in Plymouth until sometime in the 1970s, when the current main post office located in South Pond was built.

Non-post office box holders in Plymouth Center use the zip code of 02360.

[3] According to the United States Census Bureau, the CDP has a total area of 10.1 km2 (3.9 mi2), of which 5.9 km2 (2.3 mi2) is land and 4.3 km2 (1.6 mi2) (42.20%) is water.

As of the census[5] of 2000, there were 7,658 people, 3,286 households, and 1,744 families residing in the CDP.

36.6% of all households were made up of individuals, and 13.3% had someone living alone who was 65 years of age or older.