Two passenger trains collided in Naperville, Illinois, leaving 45 people dead and some 125 injured.

The Naperville train disaster occurred on April 25, 1946, on the Chicago, Burlington and Quincy Railroad at Loomis Street in Naperville, Illinois, when the railroad's Exposition Flyer rammed into the Advance Flyer, which had made an unscheduled stop to check its running gear. The Exposition Flyer had been coming through on the same track at 80 miles per hour (130 km/h). There were 45 deaths and some 125 injuries. This crash is a major reason why most passenger trains in the United States have a speed limit of 79 mph (127 km/h).

Naperville is a city in DuPage and Will counties in the U.S. state of Illinois. It is a southwestern suburb of Chicago located 28 miles (45 km) west of the city on the DuPage River. As of the 2020 census, its population was 149,540, making it the state's fourth-most populous city.