Bethlehem is a town in Litchfield County, Connecticut, United States. The population was 3,385 at the 2020 census, down from 3,607 at the 2010 census. The town is part of the Naugatuck Valley Planning Region. The town center is a historic district and a census-designated place. The town's name has prompted thousands of visitors each December to mail their Christmas cards at the renowned local post office, situated at 34 East Street, in order to get a "Bethlehem" postmark.