The fleeting and sporadic success of the early Keweenaw mines gave pause to those investors that had hoped to make it rich on the regions copper riches. With the exception of the Cliff and Central, most mines on the peninsula's northern end were abysmal failures. But little did anyone know at the time that the region's true riches were yet to be discovered, hiding deep under the highlands north of Portage Lake. For here would soon be discovered the highly rich Calumet and Kearsarge Lodes, which accounted for over 60% of all copper ever produced in the Copper Country.
It was with the discovery of the Calumet Conglomerate Lode under Calumet that gave birth to the region's largest and most profitable mine - the great Calumet & Hecla. Others would soon follow, in search of riches for their own. It wasn't long before other lodes were discovered, and some of the area's most notorious mines were established including the Tamarack and Osceola. In the end nearly two dozen mines and over a hundred shafts sprouted up along this narrow stretch of land between Calumet and Mohawk. In their shadows were born numerous towns and communities, which soon combined to created a the sprawling metropolis of Calumet - some 30,000 strong.
The burgeoning central range of the Keweenaw required a convenient deep water port to serve it. With the ports to the north too small and too distant to adequately meet their needs, these new mines turned to the primitive waterway along the Portage Valley. In the ensuing years various private and government agencies made improvements to the route - cumulating with the dredging of a canal through the last few miles of land that still connected the peninsula to the mainland. With the waterway's completion, the largest ships of the day could make their way up the Portage to deliver supplies and ship out products. By the end of the century this new transportation corridor would help the Portage Valley become the commercial and transportation hub for the entire peninsula - creating the cities of Houghton and Hancock in the process.
Besides ports, these mines also required mills to work their copper spoils. The companies turned to nearby Torch Lake to provide the necessary water and tailings reservoir these mills needed. By deepening the lakes natural inlet to Portage Lake to the south, the mines could also use the lake for delivering supplies and shipping out copper. Soon the entire western shore of would be choked full of mills, smelters and coal docks. Towns sprung up overnight, and several railroads were quickly built connecting the region with the mines atop the hill.