The Town of Plattekill is in the southeast part of the county. The town is immediately north of the Town of Newburgh.
The five official hamlets in the town include Ardonia, Clintondale, Modena, New Hurley, and Plattekill.
The town was settled early in the 18th century. The Town of Plattekill was established in 1800 from part of the Town of Marlborough.
The population of the town in 1900 was 1,866.