CN inherited the Duluth, Missabe,& Iron Range railroad
that brings raw iron ore to Minntac or United Taconite mills
where it is processed with limestone into concentrated ore
pellets called Taconite. Then the RR hauls the taconite back
thru Proctor yard and down the hill to the ore docks at Duluth where it
is loaded onto Great Lakes ore boats for shipment to the steel
Mills. Most of the iron production in the country comes thru here.
https://www.railpictures.net/photo/917135/
https://www.railpictures.net/photo/917134/