The Hull-Rust-Mahoning Mine, long called the “Grand Canyon of the North,” became the world’s largest open pit iron mine after beginning in 1895 as separate mines named for their owners that gradually merged into one. In the midst of the Mesabi Range, Minnesota’s largest iron ore range, its shallow deposits of high-grade, soft ore and the perfection of giant steam shovels at this site allowed companies to use the open pit method to remove ore quickly and economically, loading it into rail cars on tracks circling the pit. Its enormous scale, measuring 1.5 by 3.5 miles and 600 feet deep, and the important developments that took place there helped make Minnesota the nation’s leading iron-ore producer. Large-scale mining demanded extensive capital, driving out small local developers and bringing control to wealthy interests such as Rockefeller and Carnegie, whose mining and manufacturing operations were consolidated by J. P. Morgan in 1901 as United States Steel, then the world’s biggest corporation. The mine expanded rapidly in the early 1900s as demand for iron and steel grew for railroads, bridges, and skyscrapers, and at its peak during World War I and II it supplied as much as one-fourth of all the iron ore mined in the United States.