) Eastern ( UTC-4 ) ZIP code 02747/02748/02714 Area code(s) 508 / 774 FIPS code 25-16425 GNIS feature ID 0618279 Website http://www.town.dartmouth.ma.us/ Dartmouth is a town in Bristol County , Massachusetts , United States established in 1664. The population was 34,032 at the 2010 census. [ 1 ] compared with 30,666