Williamstown is a town in Oswego County, New York, United States. The population was 1,277 at the 2010 census.

Oswego County is a county in the U.S. state of New York. As of the 2020 census, the population was 117,525. The county seat is Oswego. The county name is from a Mohawk-language word meaning "the pouring out place", referring to the point at which the Oswego River feeds into Lake Ontario at the northern edge of the county in the city of Oswego. The county is part of the Central New York region of the state.