CHARLEROI, a borough of Washington county, Pennsyl vania, U.S.A., on the Monongahela river, 23m. S. by E. of Pitts burgh ; served by the Pennsylvania railroad. The population in 192o was 11,516 (26% foreign-born white), and was 11,260 in 1930 by the Federal census. It is in the "Pittsburgh" coal-field, and has important manufactures of steel, plate-glass, lamp chimneys and bottles. The factory output in 1925 was valued at 968. Charleroi was founded in 189o.