He was successful in elections to County Coroner and Allegheny County Sheriff in 1881. After his service as Sheriff he ran successfully for Pittsburgh mayor. During his term in office he led the charge for prolific construction of critical infrastructure that the rapidly developing city required to be successful. He oversaw the opening of Schenley Park in 1889. Pittsburgh's industrial might was displayed for the world during McCallin's reign as mayor when the first mold of aluminum was cast in the city.
