The Peninsula 400 was a daily express passenger train operated by the Chicago and North Western Railway between Chicago and Ishpeming, from 1942 to 1969.
It was one of the railroad's 400 passenger trains, whose name stemmed from the original '400-mile, 400-minute' express operated by the railroad between Chicago and Minneapolis–St. Paul.
Other 400s were the Shoreland 400, Valley 400, Twin Cities 400, and Flambeau 400, taking the upper middle class of Chicago with vacation time, to their fishing cabins in the northern woods of Wisconsin and Michigan's Upper Peninsula
"The Peninsula 400" can be seen in the 1959 film Anatomy of a Murder in scenes filmed at the Ishpeming, Michigan train station.