The Chicago Union Station Company (reporting mark CUST) was a wholly owned subsidiary of Amtrak that owned Chicago's Union Station, the largest intercity station in the Midwest, as well as the approach tracks. It was originally owned equally by four companies - the Pittsburgh, Fort Wayne and Chicago Railway and Pittsburgh, Cincinnati, Chicago and St. Louis Railroad (two Pennsylvania Railroad subsidiaries), the Chicago, Burlington and Quincy Railroad (Burlington Route), and the Chicago, Milwaukee, St. Paul and Pacific Railroad (Milwaukee Road) - and has been wholly owned by Amtrak since 1984. In 2017, the Chicago Union Station Company was dissolved into Amtrak.