Charleroi (/ˈʃɔːlərɔɪ/ SHAW-lə-roy) is a borough in Washington County, Pennsylvania. It lays along the Monongahela River. It is 21 miles south of Pittsburgh.[1] Charleroi was settled in 1890 and incorporated in 1891.[2] The 2020 census recorded a population of 4,234.[3]