This behemoth locomotive is the Duluth, Missabe & Iron Range (DM&IR) 2-8-8-4 "Yellowstone" which is now preserved at Two Harbors, Minnesota. Eighteen of these powerful coal burning locomotives were built between 1941 and 1943. The 2-8-8-4s were retired between 1958 and 1963 as diesel locomotives took over. Sadly, only three of the 2-8-8-4s still survive...Number 229 pictured above, Number 227 at the Lake Superior Railroad Museum in Duluth, Minnesota, and Number 225 in Proctor, Minnesota.
Under the Whyte notation, a 2-8-8-4 is a steam locomotive which has two leading wheels, two sets of eight driving wheels, and a four-wheel trailing truck.
The Duluth, Missabe and Iron Range's locomotives are among the largest steam locomotives in the world.
What were these giant locomotive used for? To haul iron ore in Minnesota. Iron ore is incredibly heavy and the DM&IR operated long trains of ore cars (one is seen below) with 115 ore cars on average. Hence the need for a locomotive that could deliver maximum power.
The 2-8-8-4 locomotives were not the fastest locomotives at the time, but they were the most powerful, and performed the job they had to do very well. I can only imagine the sight and sounds of these locomotives pulling 115 very heavy ore cars across Minnesota. I'm sure it must've been spectacular.