Donegal is a borough in Westmoreland County, Pennsylvania, United States. It is a distinct municipality from the adjacent Donegal Township. The population was 165 at the 2000 census. Donegal is best known as an exit on the Pennsylvania Turnpike with restaurants, gas stations, and a hotel for travelers. It was named after the town and county of Donegal in Ireland. Donegal has an elementary school for its children and for the children of several other area communities. As part of the Mount Pleasant Area School District, older students attend Mount Pleasant Area Junior/Senior High School.