The history of Trinity is directly linked to mineral exploration and mining activities in the upper Chiwawa valley. The first ore discovery in the area was made several miles northeast of the townsite. The find contained some gold, but was primarily chalcopyrite (copper) ore. Between 1892 and 1918, a number of companies including the Chelan Mining Company established claims in the area looking for gold and silver.
Most of these mining companies failed to find anything of value and ceased operation. In 1918, F. J. Naughten, a stockholder of the failed Chelan Mining Company and a priest in the Catholic church, hired P. J. Lonergan, a mining engineer, to investigate certain claims on Phelps Ridge. The mining engineer determined there was little gold or silver, but significant copper. The priest recruited his brother, James Naughten, a miner in Butte Montana, and together with the mining engineer created the Royal Development Company.
Early mining operations commenced in 1918 about a mile north of the current hydropower intake. Heavy snowfall and avalanches in the narrow valley forced them to abandon work in the winter and seek a better way to mine the copper ore year around.
The solution was to move the entire operation to the opposite side of Phelps Ridge, to the location now known as Trinity. There was no danger of avalanches and blasting a tunnel 11,000 feet into the mountain would provide year-around access to the ore. This enlarged operation required capital, equipment, and power.
Royal Development sold stock and raised $4,000,000 to fund the mine. By 1923, a tunnel was started and a company town was growing at Trinity. To provide power to the town and mine, the first unit of the power project was established across the Chiwawa River on James Creek, due west of the Trinity town site. This plant was not enough to sustain the growing mining operation, so in 1926 a larger power plant was proposed and constructed. (This second plant still powers Trinity today.)
About 1938 the mine closed for economic reasons. Apparently the ore was not of sufficiently high grade to support continued mining. In 1946, the Royal Development Co. went into receivership and the mine was sold to Western Machinery Co. Western Machinery salvaged everything except the power plant and sold everything that remained to a Seattle resident.
Trinity has been privately owned ever since. The current owner is the Trinity Conservancy, a group dedicated to preserving what remains of this historic site.