Illinois Service

The Illinois Service, branded Amtrak Illinois, comprises three passenger rail routes operated by Amtrak in the American state of Illinois. The Illinois Service is funded primarily by the Illinois Department of Transportation (IDOT) and falls under the broader Amtrak Midwest brand.

Chicago is a terminus for all three Illinois Service routes, which all have multiple daily round trips:
 * Chicago–Quincy: two round trips daily, the Illinois Zephyr and the Carl Sandburg
 * Chicago–St. Louis Lincoln Service: four round trips daily and the only route that serves another state
 * Chicago–Carbondale: two round trips daily, the Illini and the Saluki, and the only route whose trains have checked baggage service

Proposed expansion
Two proposed Illinois Service routes have been accepted by the Corridor Identification and Development Program, both in December 2023:
 * Chicago–Peoria Prairie Marksman via Joliet, Morris, Ottawa, and LaSalle-Peru
 * Chicago–Moline Quad Cities: uses the existing Chicago–Quincy route between Chicago and Princeton, branching from it west of Wyanet to serve the Quad Cities via Geneseo

The Quad Cities and the Rockford-Chicago portion of the Black Hawk were to have been added in late 2015 but were put on hold by then-Governor Bruce Rauner. They were resurrected and funded in 2019 as part of a transportation bill supported by Governor J.B. Pritzker. In 2023, Pritzker announced that the Rockford-Chicago train will be operated by Metra.

In addition to the two new routes, a committee was formed in late 2021 to study and promote extending the Chicago–Quincy route to Hannibal, Missouri.