Central Midland Railway (CMR), a division of Progressive Rail Inc. of Minnesota, provides regular freight rail service to several businesses located in Maryland Heights. CMR operates the far eastern segment of the former Chicago, Rock Island and Pacific Railway's St. Louis to Kansas City main line that was constructed in 1870. The active portion of the former CRI&P line runs from the north side of St. Louis, where it connects with the Terminal Railroad Association of St. Louis and Union Pacific Railroad, and now terminates in Union.