[1] But in August, the US Surface Transportation Board (STB) blocked the CN deal, ruling that the company could not use a voting trust to assume control of KCS because it might reduce competition in the railroad industry.

[6] At the STB hearings, CP and KCS defended their merger proposal, arguing that Houston has sufficient capacity to support the projected increases in traffic.

The Board suggested, to mediate between the disputing parties, the possibility that, pending merger approval or post-merger, KCS or eventually CPKC, apply to UP for trackage rights from Texarkana to Laredo via San Antonio and Austin to reroute part of the north-south traffic, bypassing Houston.

[17] Seven days after the merger, the company announced that it had landed its first major contract, handling Schneider National intermodal traffic between the U.S. and Mexico.

[18] The announcement was seen as backing up pre-merger projections that CPKC's single-line service would enable it to compete in the Chicago–Mexico corridor that had been dominated by the Union Pacific and BNSF.

[19] In response, on April 24, Union Pacific responded by announcing a partnership with Canadian National Railway and Grupo México (owner of Ferromex and Ferrosur) to work together to accelerate the exchange of intermodal traffic between Mexico and Chicago or further north into Canada.

[20] On May 11, 2023, CPKC launched its "Mexico Midwest Express (MMX)" service, numbered I180 and I181, which is mainly oriented to intermodal and automobile transportation, and also provides an approximate travel time of 98 hours between Chicago and Kansas City to Monterrey and San Luis Potosi, shorter times than those offered by the "Falcon Premium" service of UP, CN and Grupo México.

[21] Previously, and as part of preparatory moves for the day after the merger, CP and KCS launched a series of test interline services between the Lázaro Cárdenas Port in the Michoacán Mexican state and the Bensenville Yard in Chicago.

Currently, CSX traffic bound for Mexico is exchanged with the Union Pacific in New Orleans, who then takes it to the cross-border gateway in Laredo, Texas, where it is delivered to CPKC.

Haverty, who served as KCS CEO and president from 1995 to 2015, was the driving force behind the company's expansion to Mexico during his tenure, acquiring Tex-Mex in 1995 and then, that same year, win along with Transportadora Maritima Mexicana (TMM), the concession of the Mexican Northeast Railroad under the name Transportadora Ferroviaria Mexicana (TFM), which would ultimately become the catalyst for CP to acquire KCS.

[28][29] The CN and Amtrak requests were rejected by the STB, on the grounds that the two daily train pairs that CPKC and CSX plan to interchange across the M&B line will not cause congestion on the Speedway.

[29][30] In August 2023, UP and CPKC butted heads again, this time over the trackage and haulage rights that KCS once held between the "south end" in Kansas City and Council Bluffs, Iowa, over UP tracks.

CPKC informed the STB that UP was blocking the trackage and haulage rights originally granted to KCS for grain shipments from the Omaha/Council Bluffs area to Gulf Coast ports, and dating back to the merger between the Missouri-Kansas-Texas Railroad (MKT), better known as "The Katy", and UP in 1988.

When UP acquired the Katy, the Interstate Commerce Commission (ICC) required UP, as a condition of merger approval, to grant other railroads (including KCS) trackage and haulage rights to operate in the "Omaha/Council Bluffs-Kansas City corridor, with a further ability to move the grain traffic originating in this area to the Gulf."

[33][34][35] On April 24, 2024, as part of the company's first anniversary celebrations, the Steam locomotive CPR #2816 known as "The Empress" was launched on a historic transnational tour that will travel most of CPKC's network from Calgary, ending June 7 in Mexico City.

[40] In Mexico, CPKC has spent more than $75 million to build new sidings, double-track sections, bypass tracks, add yard leads, and create faster turnouts.

[53] Company executives said that merging CP and KCS would be "straightforward" because the railroads only touch at Kansas City, and interchange volumes were relatively low, with about four trains per day as of September 2021.