The IC was one of the earlier Class I railroads in the US. Its roots stretch back to abortive attempts by the Illinois General Assembly to charter a railroad linking the northern and southern parts of the state of Illinois. In 1850 U.S. President Millard Fillmore signed a land grant for the construction of the railroad, making the Illinois Central the first land-grant railroad in the United States.
The Illinois Central was officially chartered by the Illinois General Assembly on February 10, 1851. Upon its completion in 1856, the IC was the longest railroad in the world. Its main line went from Cairo, Illinois, at the southern tip of the state, to Galena, in the northwest corner. A branch line went from Centralia (named for the railroad) to the rapidly growing city of Chicago. In Chicago, its tracks were laid along the shore of Lake Michigan and on an offshore causeway downtown, but landfilling and natural deposition have moved the present day shore to the east.
In 1867 the Illinois Central extended its track into Iowa. Throughout the 1870s, and 1880s the IC acquired and expanded railroads throughout the southern United States. IC lines crisscrossed the state of Mississippi and went as far as New Orleans, Louisiana to the south and Louisville, Kentucky in the east. In the 1880s, northern lines were built to Dodgeville, Wisconsin, Sioux Falls, South Dakota, and Omaha, Nebraska. Further expansion continued into the early twentieth century.
On August 10, 1972 the Illinois Central Railroad merged with the Gulf, Mobile and Ohio Railroad to form the Illinois Central Gulf Railroad. On October 30 that year the Illinois Central Gulf commuter rail crash, the company's deadliest, occurred. In the 1980s, the railroad spun off most of its east-west lines and many of its redundant north-south lines, including much of the former GM&O. Most of these lines were bought by other railroads, including entirely new railroads, such as the Chicago, Missouri and Western Railway, Paducah and Louisville Railway and Chicago Central and Pacific Railroad. On February 29, 1988, the ICG dropped the "Gulf" from its name and again became known as the Illinois Central Railroad.
The IC is now controlled by CN's holding company Grand Trunk Corporation. The IC name continued to be used until after the railroad's sesquicentennial in 2001, after which the IC corporate identity slowly faded through CN's maintenance and repainting programs. IC locomotives repainted into the CN paint scheme retain "IC" reporting marks and sub-lettering on the sides of locomotive cabs.
Illinois Central's most famous train was the Panama Limited, a premier all-Pullman car service between Chicago, St. Louis, Missouri, and New Orleans. In 1967, due to losses incurred by the operation of the train, the Illinois Central combined the Panama Limited with a coach-only train called the Magnolia Star. On June 1, 1971 Amtrak took over the operation of the service, but shortly afterward dropped the name in favor of the City of New Orleans, a daytime streamlined coach train that had been operated by the Illinois Central whose name was popularized by a song written by Steve Goodman and performed by Arlo Guthrie (Willie Nelson made the song #1 in 1984.). Illinois Central ran several other trains along the main route including The Creole and The Louisiane.
The Green Diamond was the Illinois Central's premier train between Chicago, Springfield and St. Louis. Other important trains included the Hawkeye which ran daily between Chicago and Sioux City and the City of Miami eventually running every other day between Chicago and Miami via the Atlantic Coast Line, The Central of Georgia Railroad and Florida East Coast Railway.
After 1971 Amtrak operated the Panama Limited, later re-named City of New Orleans, over the Illinois Central mainline and the Shawnee between Chicago and Carbondale, Illinois. Amtrak presently runs three trains daily over this route, the City of New Orleans and the Illini and Saluki between Chicago and Carbondale. Another Illinois corridor service is planned for the former "Blackhawk" route between Chicago-Rockford and Dubuque. This service, subsidized by the State of Illinois is slated to begin in 2009.