The Minnesota 400 began service in a similar way to the original Twin Cities to Chicago 400, with heavyweight passenger cars pulled by an ordinary, non-streamlined steam locomotive.

In 1938, more passenger cars were added to the trains, so the locomotives were replaced by class E-S 4-6-2 Pacifics, with streamlined shrouds.

As the line served Rochester and its famous Mayo Clinic, there was at least one car on each train with wider doors for allowing patients on stretchers and other accommodations.

[1] On August 8, 1937, the C&NW extended the Minnesota 400 south to Chicago via Madison and Janesville, Wisconsin.

The southbound train bypassed Wyeville on the Elroy-Sparta cutoff; Milwaukee passengers connected at Madison.