US Post Office-Cortland is a historic post office building located at Cortland in Cortland County, New York. It was built in 1913-1915 and enlarged in 1940–1941. It is one of a number of post offices in New York State designed by the Office of the Supervising Architect of the Treasury Department, Oscar Wenderoth. It is a one-story building with a brick foundation clad in granite with facades clad in coursed ashlar limestone in the Neoclassical style. The lobby features a wood relief by Ryah Ludins in 1942-1943 titled "Valley of the Seven Hills." It was listed on the National Register of Historic Places in 1988.