Jacksonville is a hamlet in Tompkins County, New York, United States. As of the 2020 census, Jacksonville had a population of 516. The community is located within the Town of Ulysses, along New York State Route 96. It is 3.5 miles (5.6 km) southeast of Trumansburg. Jacksonville has a post office with ZIP code 14854, which opened on February 25, 1820.