In July 1880, Victor E. Tull of the Black Diamond Coal Mining Co. of California finds high-quality coal deposits on the Green River. Lower-quality coal had been observed in the area near the surface as early as 1873, but the deep valleys and thick timber prevented development. The discovery is kept quiet until the company can buy up land for mines. Commercial production from the Green River Coal Field will await the extension of the Columbia and Puget Sound Railroad up the Cedar River from Renton.
In the 1870s and 1880s, the largest customer for coal on the West Coast was San Francisco. Supplies came from mines on Mount Diablo and from mines on Puget Sound. The mines at Newcastle and Renton shipped coal by rail to Seattle where the coal was loaded on ships. By 1882, three ships each made five round trips a month between Seattle and San Francisco laden with coal.
On June 26, 1873, Edgar E. Morgan and others incorporated The Green River Coal Co. to exploit seams of coal found near the surface, but nothing came of the venture because there was no transportation. As the Mount Diablo mines declined in the 1870s, Pierre Barlow Cornwall, president of the Black Diamond Co. sent Victor Tull to survey new sources on Puget Sound. In the thick stands of trees on the plateau between the Green and Cedar Rivers, he found good-quality coal below the surface.
Black Diamond began discreetly buying up land, but the process was complicated by laws limiting the property that mining companies could claim and by ownership of alternating sections of land by the Northern Pacific Railroad. Rumors began to fly around Seattle about a mysterious California company "with limitless capital" looking to mine coal on the Green River (Daily Chronicle quoted in Thorndale). The Northern Pacific Railroad, through its subsidiary the Oregon Improvement Co., also needed coal and made plans to exploit the field.
Construction of Black Diamond Mine No. 14 began in January 1882. The railroad reached Black Diamond in December 1884. Commercial production began in April 1885. Mines at Franklin, Ravensdale, Cedar Mountain, and Lawson followed.
