In 1937, the U.S. Post Office moved out of its original building on Market Street ( CA13) into this modern, polished black granite building designed by Lorimer Rich (1891–1978). A graduate of Syracuse University, Rich designed several buildings for his alma mater. He served in World War I, then worked for New York architect Charles A. Platt and studied at the American Academy in Rome. From 1922 to 1928, he was in the office of McKim, Mead and White. After leaving that firm, Rich won his most famous commission: the design for the Tomb of the Unknowns at Arlington National Cemetery with sculptor Thomas Hudson Jones. While in private practice, Rich designed at least eight post offices in New York City, including what he felt was his best work, the Brooklyn Station. The Johnstown building is so similar to his design for the Forest Hills Post Office in Queens, New York, that one set of plans may have been used for both.
This building is a smooth black box with stylized eagles on heavy pedestals at the edge of the entrance, and six three-story strips of recessed windows across the facade. The windows are spaced along the facade and side elevations with the same even rhythm as the columns on older Greek Revival post offices, like the post office on Market Street that this one replaced. The starkly stylized exterior is a superb Moderne expression.