The mining districts of the Western or Cordilleran States are numerous and scattered over wide areas. The first attempt to locate all of them on a single map was carried out by the writer in 1907, with the aid of Mr. J. M. Hill and the statisticians in charge of the offices of the Survey at Denver, Salt Lake City, and San Francisco (Messrs. Chester Naramore, V. C. Heikes, and C. G. Yale). This map of the Western States was included in the annual volume of Mineral Resources of the United States. The large area covered and the necessity of adding explanatory tables made this map cumbersome to handle. When a revision was decided upon in 1910 and assigned to Mr. J. M. Hill, it was found advisable to map the several States separately and publish the maps, with more extensive explanatory text, in the convenient form of a bulletin.
US Department of the Interior, "The Mining Districts of the Western United States" (1912). Federal Documents. 19.