Harrison County is located in the far southern part of the U.S. state of Indiana along the Ohio River. The county was officially established in 1808. Its population was 39,654 as of the 2020 United States Census. Its county seat is Corydon, the former capital of Indiana.

Corydon is a town in Harrison Township, Harrison County, Indiana. Located north of the Ohio River in the extreme southern part of the U.S. state of Indiana, it is the seat of government for Harrison County. Corydon was founded in 1808 and served as the capital of the Indiana Territory from 1813 to 1816. It was the site of Indiana's first constitutional convention, which was held June 10–29, 1816. Forty-three delegates convened to consider statehood for Indiana and drafted its first state constitution. Under Article XI, Section 11, of the Indiana 1816 constitution, Corydon was designated as the capital of the state, which it remained until 1825, when the seat of state government was moved to Indianapolis. In 1863, during the American Civil War, Corydon was the site of the Battle of Corydon, the only official pitched battle waged in Indiana during the war. More recently, the town's numerous historic sites have helped it become a tourist destination. A portion of its downtown area is listed in the National Register of Historic Places as the Corydon Historic District. As of the 2010 census, Corydon had a population of 3,122.