Reynoldsville is a borough in Jefferson County, Pennsylvania, northeast of Pittsburgh, in a productive soft coal region. In the past, it had silk mills, brick and tile works, a tannery, a macaroni factory, and an asbestos plant to provide employment. In 1900, the population stood at 3,435 people; and in 1910, 3,189. Reynoldsville was greatly enlarged in 1913 when it annexed West Reynoldsville (population 993 in 1910) and three large adjacent areas. The population was 2,710 at the 2000 census.
Reynoldsville was originally called Winslow Township and was renamed after local postmaster Thomas Reynolds in 1850.