Greenville is a borough with home rule status in northwestern Mercer County, Pennsylvania, United States. Located along the Shenango River, it lies roughly 80 miles from both Pittsburgh and Cleveland. It is 1.89 square miles in area, and had a population of 5,541 as of the 2020 census.

Mercer County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 110,652. Its county seat is Mercer, and its largest city is Hermitage. The county is part of the Northwest Pennsylvania region of the state.