Copper Harbor became the nucleus of early mining activity on Lake Superior as a supply depot, gathering place and point of departure for exploring parties, miners and land speculators. Small craft enlivened its waters, and the surrounding shoreline was dotted with the tents of temporary inhabitants.

The influx of fortune-seekers at Copper Harbor required federal supervision to maintain law and order. Early in 1843, a Mineral Land Agency was established on Porter’s Island to regulate the system of exploration permits and land leases devised to prevent conflicting land claims. The agent was instructed to prevent squatters from occupying mineral lands without a government permit and was authorized to draw upon military support at distant Fort Brady, Sault Ste.Marie, to keep order.

A former Pittsburgh druggist, John Hays, who visited the Lake Superior Copper District in 1843, secured an interest in the holdings of a Boston- based mining firm. With the financial support of other Pittsburgh businessmen, Hays and his partner, Dr. C. G. Hussey, organized the Pittsburgh and Boston Copper Harbor Mining Company in May 1844. The mining company began operations on Hays Point, at the eastern end of Copper Harbor. Three unsuccessful shafts were sunk before the company located a mass of copper one hundred yards east of Fort Wilkins. A labor force of 70 miners sank three shafts and extracted 40 tons of copper, worth $4500, before the site was abandoned as a failure.

By 1849 mineral activity had shifted from the Copper Harbor vicinity to locations further south. Among the new sites was the Cliff Mine, discovered by John Hays, and operated by the Pittsburgh and Boston Mining company. In 1849, the Cliff became the first successful copper mine in North America, returning dividends of $10 per share to its stockholders. Ultimately, profits from the Cliff paid a 2,000 per cent return on the original investment.