The St. Louis Southwestern Railway Company, known by its nickname of "The Cotton Belt Route" or simply "Cotton Belt", was a Class I railroad that operated between St. Louis, Missouri, and various points in the U.S. states of Arkansas, Tennessee, Louisiana, and Texas from 1891 to 1980, when the system added the Rock Island's Golden State Route and operations in Kansas, Oklahoma, and New Mexico. The Cotton Belt operated as a Southern Pacific subsidiary from 1932 until 1992, when its operation was assumed by Southern Pacific Transportation Company.

The Southern Pacific was an American Class I railroad network that existed from 1865 to 1996 and operated largely in the Western United States. The system was operated by various companies under the names Southern Pacific Railroad, Southern Pacific Company and Southern Pacific Transportation Company.