CMR's first leased-segment was Union Pacific's "Lackland Subdivision" which extends from "Rock Island Junction" near the intersection of Page Avenue and I-170 in Overland to a location on the north-side of Creve Coeur Lake in Maryland Heights, Missouri, known as "Vigus."
On March 31, 1980, the Rock Island ceased all operations as a condition of its bankruptcy, and the line was passed into the hands of the Kansas City Terminal Railroad.
Soon after, the line was sold as part of a package deal which included the Kansas City to Tucumcari, New Mexico, "Golden State Route" to the St. Louis Southwestern Railway (SSW).
[2] However, due to years of deferred maintenance by its previous owner, bringing the line up to modern class 1 mainline standards was deemed uneconomical by the SSW.
To regulate the route's competitive impact on UP's parallel ex-Missouri Pacific St. Louis to Kansas City main line, UP retained ownership of the extreme east and west ends of the Rock Island; specifically, from "Rock Island Junction" in Overland, Missouri, to "Vigus" in St. Louis County on the east, and between Pleasant Hill and Kansas City on the west.
On March 1, 2022 the CMR officially ceased operations and was taken over by successor Missouri Eastern Railroad, which is a subsidiary to Jaguar Transport Holdings, LLC.