The Duluth, Missabe & Iron Range Railroad owned 18 Yellowstone type 2-8-8-4 simple articulated engines, which were used to haul ore cars between the northern Minnesota mines and Lake Superior docks. Their design was based not on the Northern Pacific's original Yellowstones but on a Western Pacific 2-8-8-2 type. No. 235, shown above in a mid-1950s photo of unknown origin, belonged to the second group delivered by Baldwin in 1943 as class M4.
Weighing 628,700 pounds without their 4-10-0 centipede-type tenders, the M4s delivered 140,000 pounds of tractive effort. They had 63-inch disc drivers and four 26x32-inch cylinders, and sustained 240 p.s.i. of boiler pressure. They had an evaporative heating surface of 6780 square feet and a superheater surface of 2780 square feet. The DM&IR Yellowstones were among the last North American steam engines used in regular service, some not being retired till 1963. Three examples survive on display in Minnesota, not including No. 235. For another view of this massive locomotive, click here.