The US Post Office—Newburyport Main is a historic post office in Newburyport, Massachusetts. Construction of the Georgian Revival single story brick building was begun in 1927 and completed in 1928. It was Newburyport's first purpose-built post office facility. The building is faced in red brick laid in running bond. Its central section, which houses the lobby area, projects slightly from wings on either side, and features three round arches trimmed in marble. The wings house offices, and the rear of the building houses the service area. The front block has a pitched hip roof, while the rear portion has a flat roof.