[2] A lightweight streamlined train, the Pioneer Zephyr, was introduced in 1934 the United States by the Chicago, Burlington and Quincy Railroad.

The C&NW Chicago to St. Paul Viking train used this route through Madison, taking about 12 hours.

This railroad met the Omaha Railway in Wyeville, Wisconsin as part of the new route between Milwaukee and St. Paul, but not going through Madison.

It became the route for the overnight North Western Limited, which used heavyweight Pullman cars between Chicago and the Twin Cities.

[6][7] Attention then turned to faster trains to Saint Paul: The CB&Q ran a Zephyr demonstration train between Chicago and the Twin Cities that summer with the intent to run regular service the next year, and the Milwaukee Road introduced similar plans.

Other 400 trains would receive similar instructions in later years, and the rule remained in effect for most of the Twin Cities 400's existence.

In 1952 the railroad installed automatic train stop along the eastern half of the route from Chicago to Wyeville due to regulations from the Interstate Commerce Commission.

Today, the Twin Cities to Chicago route is served by the Amtrak Borealis, which takes about seven hours.

On July 30, 1959, the Twin Cities 400 left the rails between Knapp and Menomonie in Dunn County, Wisconsin.

This stood in stark comparison to the Milwaukee Road's Hiawatha and the Burlington Zephyrs, each of which first ran with brand new locomotives and cars.

C&NW updated the train in 1939 with two pairs of EMD E3A locomotives and lightweight streamlined passenger cars.

It ran to Milwaukee on the lakefront commuter line and stopped at the Lake Front Depot on Wisconsin Avenue.