During the early years of the copper boom, over two dozen shafts were sunk into the high ridge line atop Houghton from no less then thee separate mines: the Huron, Grand Portage, and Isle Royale. By the end of the century these mines had all been consolidated under the Isle Royale name and the company took another look at its massive holdings with renewed interest. Before long the new consolidated company would find itself working a highly profitable stretch of land, a rich deposit of copper that would continue to nourish the mine for another 30 years.
In terms of surface holdings the Isle Royale Mine was one of the largest single mines in the Keweenaw, stretching south of Houghton for over two miles, compassing over 3500 acres of mineral-rich lands in the process. At its peak the mine had a workforce of over 700 men, helping to grow the nearby city of Houghton as well as creating the mining towns of Dodgeville and Hurontown in the process. While successful, the mine would prove to be no match for the arrival of the great Depression. The mine was forced to close in 1932. Buoyed by high copper demand and government contracts the mine was re-opened shortly during the Second World War, but finally closed for good soon after.
At first the Isle Royale mine simply re-opened two of its original shafts along the lode, but as the copper accessible by these shafts began to diminish the company expanded southward in search of more copper. These new shafts – including the No. 6 – were sunk into the old mineral lands of the defunct Huron and Dodge properties. In the end the company had a total of six shafts working the Isle Royale Lode, and became one of the Keweenaw’s largest mining companies in the process.