The Porcupine Gold Rush was a gold rush that took place in Northern Ontario starting in 1909 and developing fully by 1911. A combination of the hard rock of the Canadian Shield and the rapid capitalization of mining meant that smaller companies and single-man operations could not effectively mine the area, as opposed to earlier rushes where the gold could be extracted through placer mining techniques. Although a number of prospectors made their fortune, operations in the area are marked largely by the development of larger mining companies, and most people involved in the mining operations were their employees. The mines peaked between the 1940s and 50s, but continue to produce gold to this day, although the many smaller mines have been consolidated into a small number of larger holdings. By 2001, 67 million troy ounces of gold have been mined from the Porcupine area, making it by far the largest gold rush in terms of actual gold produced. For comparison, the well-known Klondike Gold Rush produced about 12 million troy ounces.
By the spring of 1910 the rush was in full swing. Thousands of fortune seekers poured into the area, either in an attempt to stake their own claims, or more and more commonly, looking for work in high paying mining jobs. Towns, often nothing more than tent camps, sprung up along the banks of Porcupine Lake, at that point the terminus of the canoe route into the area. Golden City (later Porcupine) and Pottsville sprung up almost overnight, followed by South Porcupine at the end of the lake, closer to the main mining areas. As the area was quickly explored and staked, the main gold producing area was revealed to be three miles (5 km) wide and five long, running along an east-west axis southwest of the lake. Mines all along the area started production over the next few years, buying plots staked during 1910 and 1911. Seeing the obvious potential of the area the T&NO started construction of a spur line, but was delayed by the constant defection of workers to the goldfields. The province responded by shipping prisoners to work the line, handing secondary duties such as clearing trees and rock. The spur reached Golden City on June 7, 1911, and an official opening followed on July 1. More people poured into the towns, and by the end of the summer there were 8,000 active claims.