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.
This line is not found in the 1870 maps
The earliest ancestor to the Alton Railroad was the Alton and Sangamon Railroad, chartered February 27, 1847, in Illinois to connect the Mississippi River town of Alton to the state capital at Springfield in Sangamon County. The line was finished in 1852, and as the Chicago & Mississippi Railroad extended to Bloomington in 1854 and Joliet in 1855. Initially trains ran over the completed Chicago and Rock Island Railroad to Chicago. The Joliet and Chicago Railroad was chartered February 15, 1855, and opened in 1856, continuing north and northeast from Joliet to downtown Chicago. It was leased by the Chicago & Mississippi, providing a continuous railroad from Alton to Chicago. In 1857 the C&M was reorganized as the St. Louis, Alton and Chicago Railroad, and another reorganization on October 10, 1862, produced the Chicago and Alton Railroad. The C&A chartered the Alton and St. Louis Railroad to extend the line to East St. Louis, opened in 1864, giving it a line from Chicago to East St. Louis.