The Great Southwest Railroad was a small yet vast switching railroad, chartered on May 7, 1957, to serve industries in Arlington and Grand Prairie, TX. The line was built and operations commenced two years later. It connected to the then-Texas & Pacific line in Arlington, and meandered northward to a connection with the Chicago, Rock Island & Pacific at a small community called Tarrant.

Just a year after it started operations, in 1960, 90% of the GSWRR was purchased by its two connecting railroads, the T&P and the CRI&P, each with a 45% share. In 1985, the Missouri Pacific, which had purchased the T&P, purchased the Rock Island's shares outright, giving MP complete 100% control; the GSWRR was subsequently merged into the MP in 1987.

Today, some of the tracks are still used to serve local industries by Union Pacific. While its northern connection has been severed with the Rock Island (which is now owned by the cities of Dallas and Fort Worth, on which their Trinity Railway Express commuter trains run), the southern connection with UP still sees about a train daily. Some of the spurs have since been abandoned.

The map presented plots out the GSWRR in its entirety, based on 1981 topographical maps.