Dunbar is a borough in Fayette County, Pennsylvania, United States. The population was 1,013 at the time of the 2020 census, a decline from the figure of 1,042 tabulated in 2010. Dunbar is named for Col. Thomas Dunbar, who commanded an English force at nearby Jumonville and retreated to Philadelphia after Edward Braddock was defeated by th…Dunbar is a borough in Fayette County, Pennsylvania, United States. The population was 1,013 at the time of the 2020 census, a decline from the figure of 1,042 tabulated in 2010. Dunbar is named for Col. Thomas Dunbar, who commanded an English force at nearby Jumonville and retreated to Philadelphia after Edward Braddock was defeated by the French and Indians.