US Post Office-Harrison is a historic post office building located at Harrison in Westchester County, New York, United States. It was built in 1938 by the Office of the Supervising Architect under the direction of Louis A. Simon. It is a one story, symmetrically massed building clad with random stone ashlar in the Colonial Revival style. The entrance is flanked by fluted, engaged Doric order columns and pilasters which support a simple entabulature. The slate roof is topped by a square, flat topped cupola. The lobby features a 1941 mural by Harold Goodwin titled "Early Days of the Automobile."