KCS bought out TMM in 2005 and made Tex-Mex a wholly owned and consolidated subsidiary of its Kansas City Southern Railway.

Lines originally operated by Tex-Mex are now a vital link in CPKC's rail network, the first and only to directly serve Canada, Mexico and the United States.

This 52-mile (84 km) line's main purpose was to take domestic sheep from Texas ranches to the shores of the Gulf of Mexico, and received some funding from Richard King and Mifflin Kenedy.

In 1883 a bridge was built across the Rio Grande to Nuevo Laredo, making the Tex-Mex the first Mexico–United States rail connection.

The seasonal train ran on a 157-mile (253 km) route between Corpus Christi and Laredo with stops in Robstown, Alice, and Hebbronville, taking 4.5 hours.

In August 2004, KCS again purchased a controlling interest in Tex-Mex,[8] although they were held by a trust company until the Surface Transportation Board approved the move for January 2005.

In 2006, KCS and Tex-Mex announced they would rebuild the Macaroni Line, to end the need for trackage rights on a circuitous Union Pacific route.

[11][12][13] On May 23, 2018, the Tex-Mex announced they were moving the point of interchange where the railroad met Kansas City Southern de Mexico (KCSM).

The Federal Railroad Administration (FRA) approved the Tex-Mex's request to allow Mexican crews to cross the border with their trains and operate 9 miles into the U.S. to the North Laredo switching yard.

The Brotherhood of Locomotive Engineers & Trainmen (BLET) objected to the use of Mexican crews in the United States and threatened to strike over the matter.

The arbitrator ruled on July 19, 2020, that the bargaining contracts between the Tex-Mex Railway and the BLET allowed the railroad the exclusive right to determine where the point of interchange would be.