Correctionville is a city in Woodbury County, Iowa, United States. It is part of the Sioux City, IA–NE–SD Metropolitan Statistical Area. The population was 851 at the 2000 census. The town name comes from the original survey of the town. The site lies on a surveyor's correction line, which adjusts for the convergence of the meridian lines. This keeps the section boundaries approximately 1 mile apart, making all sections approximately the same size (approximately 1 square mile). This correction line is aligned with 5th street through the downtown; there are no north/south streets extending straight past 5th street.