The C.I. & L Railway was known as the Monon since its mainline from Chicago branched in Monon, Indiana.
In 1882, the railroad started printing "The Monon Route" on company maps, and later formally took the name "Monon - The Hoosier Line" on timetables, letterheads, and rolling stock. The Monon, from 1897, operating almost entirely within the state of Indiana, and was merged into the Louisville and Nashville Railroad in 1971. Much of the former Monon right of way is operated today by CSX Transportation.