Glimmerglass Historic District is a national historic district located near Cooperstown in Otsego County, New York. The 15,000-acre (61 km2) district encompasses parts of three towns, Otsego, Springfield, and Middlefield and the village of Cooperstown. It encompasses the physical and social sphere of Otsego Lake and its immediate environs. It includes 1,475 contributing features, some of which were previously listed including the Cooperstown Historic District, U.S. Post Office (Cooperstown, New York), and Hyde Hall in Glimmerglass State Park.