The Port Terminal Railroad Association was organized on July 1, 1924, as an unincorporated terminal company to provide area railroads with equal access to the Port of Houston. Prior to that date, only the International-Great Northern Railroad Company, the Southern Pacific Lines, and the Houston Belt and Terminal Railway Company served the port. However, each company only reached a small area of the port, and there was no coordinated operation covering the whole facility. The Port Terminal Railroad Association began operations over tracks owned by the city of Houston; trackage rights were provided by the Galveston, Harrisburg and San Antonio Railway Company, and tracks were constructed by the Harris County-Houston Ship Channel Navigation District (now Port of Houston Authority). By 1929 the association operated fifty-seven miles of track and sidings. On December 31, 1930, it leased the Northside Belt and later absorbed that company. As industrial development expanded along the ship channel, the Port Terminal Railroad Association also grew, and in 1993 it maintained 154 miles of track, including forty-six miles of main track about equally divided between the north side and the south side of the Houston Ship Channel. The association serves 150 industries and handles 500,000 cars annually.