Short for General American Transportation Corporation, GATX operates through a handful of business segments. Rail, with about 164,000 railcars (mostly tank and freight, plus 570 locomotives), is the company's biggest unit, handling tank, freight car, and locomotive leasing in the US and Europe. The American Steamship Company (ASC) business is a shipping company with a fleet of self-unloading ships operating on the Great Lakes. Its third segment, portfolio management, handles leases, affiliate investments, and loans for the marine, construction and mining, and manufacturing equipment industries.