Riverside is a borough in Northumberland County, Pennsylvania, United States. The population was 1,861 at the 2000 census. The current mayor is Dale E. Erb.
Riverside was established in 1871. It was merged with Gearhart Township in 1950.
Riverside is located at 40°57′13″N 76°38′06″W / 40.953663°N 76.634872°W / 40.953663; -76.634872.