 The area split off from Montgomery County was much larger than the present county, as it included the present Allegany, Cattaraugus, Chautauqua, Erie, Genesee, Livingston, Monroe, Niagara, Orleans, Steuben, Wyoming, Yates, and part of Schuyler and Wayne counties.Otsego County was one of three early counties split off from Montgomery (the other two being Herkimer and Tioga) after the American Revolutionary War.Otsego County was officially established on February 16, 1791, with Cooperstown as its county seat, although at the time the village of Cherry Valley was much larger.