Groton is located in
New London County just east of New London between Poquonock Bridge and Quaker Hill along Highway 1 on the banks of the Thames River near Fishers Island Sound. Bluff Point State Park is just southeast.
The population estimate for July 1, 1998 was 9,394, a decrease of 443 since 1990.
Groton is part of the New London-Norwich metro area.