The Illinois Zephyr and Carl Sandburg are a pair of passenger trains operated by Amtrak on a 258-mile (415 km) route between Chicago and Quincy, Illinois. As Illinois Service trains, they are partially funded by the Illinois Department of Transportation. Between Chicago and Galesburg, Illinois, the trains share their route with the California Zephyr and Southwest Chief; the remainder of the route (Galesburg–Quincy) is served exclusively by the Illinois Zephyr/Carl Sandburg.

Quincy is a city in and the county seat of Adams County, Illinois, United States, located on the Mississippi River. The population was 39,463 as of the 2020 census, down from 40,633 in 2010. The Quincy micropolitan area had 114,649 residents.