Avoiding highways and railways, Kirby Inland Marine uses waterways to carry liquid bulk cargo. The primary subsidiary of Kirby Corp., Kirby Inland Marine operates a fleet of about 915 tank barges and 240 towing vessels. Hauling petrochemicals accounts for the majority of the company's sales; other freight carried by Kirby Inland Marine includes crude and refined petroleum products and agricultural chemicals. The company's operations span the major inland waterway systems of the US, including the Mississippi River and its tributaries, the Gulf Intracoastal Waterway, the Illinois River, and the Ohio River.