The Alton Railroad (reporting mark A) was the final name of a railroad linking Chicago to Alton, Illinois, St. Louis, Missouri, and Kansas City, Missouri. Its predecessor, the Chicago and Alton Railroad (reporting mark C&A), was purchased by the Baltimore and Ohio Railroad in 1931 and was controlled until 1942 when the Alton was released to the courts. On May 31, 1947 the Alton Railroad was merged into the Gulf, Mobile and Ohio Railroad. Jacob Bunn had been one of the founding reorganizers of the Chicago & Alton Railroad Company during the 1860s.
Main lines included Chicago to St. Louis and a branch to Kansas City. The former is now part of Union Pacific, with Metra Heritage Corridor commuter rail service north of Joliet (owned by the Canadian National Railway but used by UP). The latter is part of the Kansas City Southern Railway system.(Wikipedia)