Salamanca is a city in Cattaraugus County, New York, United States, inside the Allegany Indian Reservation, one of two governed by the Seneca Nation of New York. The population was 5,929 at the 2020 census. It was named after José de Salamanca, a Spanish nobleman and cabinet minister of the mid-19th century. Salamanca invested in railroads around the globe, including the Atlantic and Great Western Railroad in New York State, Pennsylvania, and Ohio.