PTRA is an Association that performs rail switching for its members, BNSF Railway Company, Union Pacific Railroad Company, and Kansas City Southern Railway Company, on property owned by the Port of Houston. Additionally, PTRA provides linehaul and other rail services for industry customers within the Port. PTRA maintains 32 miles of mainline track (and 300 total miles) on the north and south sides of the Port. The PTRA was founded in 1924 and has been continuously operating since then.