US Post Office-Ilion is a historic post office building located at Ilion in Herkimer County, New York, United States. It was built in 1935–36, and is one of a number of post offices in New York State designed by the Office of the Supervising Architect of the Treasury Department, Louis A. Simon. It is a one-story, seven-bay, steel frame building on a raised foundation with a brick watercourse in the Colonial Revival style. The interior features a 1937 plaster relief by artist Edmond Amateis of Eliphalet Remington. It was listed on the National Register of Historic Places in 1989.