On October 22,1969, the Duluth, Missabe and Iron Range Railway Company donated to the Lake County Historical Society the Baldwin Locomotive and Tender, Class M4 Mallet #229.
Mallet locomotive #229, also known as a Yellowstone, was one of the largest locomotives made. Built in 1943, it went directly to helping transport materials during the war. When peace came, the Mallet was diverted to cross-country ore hauling between the Iron Range, Two Harbors and Duluth/Proctor. The Mallet is considered an example of a slow-drag freight articulated locomotive because, although slow, the Mallet was powerful and able to haul mile-long trains of iron ore. The Mallet located in Two Harbors is one of only three Yellowstones to be preserved.
The last Yellowstone to make a regular ore run was # 222 on July 5, 1960 on the Missabe Division. It was sent to Two Harbors and put on display for a very short time before being swapped for # 221. This engine deteriorated in the weather and was replaced in 1967 by #229, which had been stored in the Proctor roundhouse up until then. The 3 Spot and Mallet 229 represent the first and the last in the evolution of the steam locomotive on the Minnesota Iron Range.