Liberty is a town in Sullivan County, New York, United States. The population was 10,159 at the 2020 census. The town contains a village also named Liberty. The village is bisected by New York State …Liberty is a town in Sullivan County, New York, United States. The population was 10,159 at the 2020 census. The town contains a village also named Liberty. The village is bisected by New York State Route 52 and NY 55, and is crossed by NY 17.