Discovery of iron ore on the Vermilion Range and subsequently on the Mesabi and Cuyuna Ranges created an impetus for the settling of northern Minnesota and great economic wealth. Iron from those ranges fed the industrial revolution and America during both world wars.
I nominated iron ore because I am descended from Minnesota iron miners. My grandfather Hans William Johnson was born in 1895 in Soudan, Minnesota, and worked for the Oliver Mining Company at what is now the Soudan Underground Mine State Park.
~William Smith, Bemidji, MN