is a city in Boon Township, Warrick County, Indiana, United States. The population was 6,834 at the 2000 census. The city is the county seat of Warrick County. Founded in 1818 and named for Ratliff Boon, an early settler and Indiana's second governor, who supported the city becoming county seat.
President Abraham Lincoln studied law in Boonville. When Abraham Lincoln and his family moved from Kentucky to present-day Spencer County in 1816, their homestead was then considered to be within Boonville's Warrick County boundaries. The future president frequently walked to Boonville to borrow books and watch local attorney John Brackenridge argue cases, thus earning Boonville the distinction of being "where Lincoln learned the law."
According to the United States Census Bureau, the city has a total area of 3.0 square miles (7.7 km²), of which, 3.0 square miles (7.6 km²) of it is land and 0.04 square miles (0.1 km²) of it (0.67%) is water.