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 (1.6 km) 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. Correctionville has the longest single name in the state of Iowa.
Correctionville is located at 42°28′36″N 95°47′5″W / 42.47667°N 95.78472°W / 42.47667; -95.78472 (42.476697, -95.784746). The town is situated adjacent to the Little Sioux River.
According to the United States Census Bureau, the city has a total area of 0.6 square miles (1.5 km²), all of it land.