The US Post Office—Palmer Main is a historic post office building at Park and Central Streets in Palmer, Massachusetts.The single story Classical Revival building was built in 1931. It is a steel frame building with an exterior of brick and limestone. Its main entrance is centered on the long, street-facing side of the building, which is lined with columns. The interior lobby area as terrazzo marble flooring and marble wainscoting, as well as original woodwork. The building was listed on the National Register of Historic Places in 1985.