The Kentucky Cardinal was a nightly 312-mile (502 km) passenger train operated by Amtrak from 1999 to 2003 between Chicago, Illinois, and Louisville, Kentucky, via Indianapolis, Indiana. On the three days that the Cardinal ran, the Kentucky Cardinal operated as a section, splitting at Indianapolis. On the other four days, it ran on its own to Chicago.

Between May 1971–August 1974 Amtrak's Floridian ran from Chicago to Florida via Indianapolis and Louisville. Due to poor track conditions on the Penn Central trackage in Indiana, the train was rerouted to the west north of Nashville, Tennessee. In April 1975 the train was routed back east over the former Monon Railroad, again serving Louisville, but bypassing Indianapolis to the west. The Floridian served Louisville until its discontinuance in October 1979.

On December 17, 1999, the Kentucky Cardinal started running as an extension of the Hoosier State, which ran four days a week between Chicago and Indianapolis (filling in the gaps in the Cardinal schedule). The Kentucky Cardinal ran as trains 850 southbound and 851 northbound. Three days of the week, it was grouped with the Cardinal, trains 50 and 51, north of Indianapolis.

The train, operated along trackage that had last been used by the Floridian in 1974, was an attempt to attract express business from United Parcel Service, which maintains its air-express hub at Louisville International Airport. At first the train only ran from Indianapolis south to Jeffersonville, Indiana, where a new Amtrak Mail and Express facility was built. The city of Louisville spent $370,000 in 2001 to renovate its Union Station for the service, and on December 4 the Kentucky Cardinal started to use a new track on the west side of the Union Station parking lot.

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