RLI Corp is an American property and casualty insurance company headquartered in Peoria, Illinois. The company, through its subsidiaries, provides various insurance products, including casualty insurance, property insurance, and surety bonds. RLI Corp operates in all 50 states and internationally. The company was founded in 1965 and has since grown to become a Fortune 1000 company. RLI Corp is known for its strong financial performance and has consistently been rated A+ by A.M. Best.