 It has seven steam, 14 diesel, and two electric locomotives, and over 40 other pieces of rolling stock.The collection includes the William Crooks, the first locomotive to operate in the state of Minnesota, and the Duluth, Missabe and Iron Range Railway Number 227, a "Yellowstone" locomotive that was among the largest steam engines ever.Only 18 Yellowstones were ever built, and Duluth exhibits one of the three that remain.