UP Mackinaw River Bridge (Lexington)

In 1850, the Alton and Sangamon Railroad began construction on a 220 mile railroad line, extending from Joliet, Illinois to Alton, Illinois; with stations in Bloomington and Springfield, Illinois.  The railroad was acquired by the Chicago, Alton & St. Louis Railroad and completed in 1855.  The Alton and St. Louis Railroad constructed a 22 mile line from Alton to East St. Louis in 1856.  The railroads were reorganized as the St. Louis, Alton & Chicago Railroad in 1857, and was merged into the Chicago & Alton Railroad (C&A) in 1862.  The C&A developed several lines throughout central Illinois, and this route made up the principal mainline of the system.  A bypass of Alton between Godfrey and East St. Louis was constructed in As traffic grew on the system through the 1870s and 1880s, the need for a second track became apparent.  A second track was added in 1870 between Mazonia and Odell, from 1888 to 1893 between Odell and Bloomington, and through Springfield in 1893.  This route became an important route to the Illinois railroad network, providing the most direct connection between St. Louis and Chicago.

Throughout the years, the C&A would be affiliated with several larger railroads, and the railroad primarily operated as a bridge route.  The C&A was reorganized in 1901, and until 1906 was owned by the Atchison, Topeka & Santa Fe Railway and the Chicago, Rock Island & Pacific Railway.  Between Bloomington and Springfield, a second track was constructed in 1907, and a second track was constructed in 1911 between Springfield and East St. Louis.  A large realignment was made between Atlanta and Lawndale in 1924.  In 1931, the C&A would be reorganized as the Alton Railroad (A), a subsidiary of the Baltimore & Ohio Railroad.  The Alton was sold to the Gulf, Mobile & Ohio Railroad (GM&O) in 1949, and the various subsidiaries consolidated at that time.  The GM&O merged with the Illinois Central Railroad to form Illinois Central Gulf (ICG) in 1972.  During the ICG years, the route was downgraded, and the second track mostly removed.  This line was excess for the ICG, and the route would be sold to the Chicago, Missouri & Western Railway (CM&W) in 1987.  The CM&W went bankrupt, and the line was sold to the Southern Pacific Railroad in 1989, which became part of Union Pacific Railroad in 1996.  During the 2010s, the route was rebuilt for high speed rail.  Today, Union Pacific continues to operate this route as the Joliet Subdivision between Joliet and Bloomington, and the Springfield Subdivision between Bloomington and East St. Louis.  High speed Amtrak trains also utilize this route.