The West Main Street Historic District of Marlborough, Massachusetts encompasses a residential area west of the city center. It extends along West Main Street from Mechanic Street to Gibbon Street, along Pleasant Street from West Main to Lincoln Street, and also includes short pieces of Witherbee and Winthrop Streets abutting West Main. Most of the buildings in the district are houses built between 1820 and 1930, the period of the city's growth as an industrial center. The 15-acre (6.1 ha) district includes 77 properties, all but two of which contribute to its historic significance. The district was listed on the National Register of Historic Places in 2001.