Gainesville is an incorporated town in Wyoming County, New York. The population was 2,333 at the 2000 census. The town is named after General Edmund P. Gaines.

Wyoming County is a county in the U.S. state of New York in the state's western area. As of the 2020 census, the population was 40,531. The county seat is Warsaw. The name is modified from a Lenape (Delaware) Native American word meaning "broad bottom lands". Wyoming County was formed from Genesee County in 1841. Wyoming County is one of New York's mostly agricultural counties. With an estimated 47,500 dairy cows in the county, there are more cattle in Wyoming County than people. The county is part of the Finger Lakes region of the state.