Last week I reported that the USGS had posted 5,000 mineral resource dockets online including hundreds for Arizona but Jon Spencer noted that the USGS map shows nothing for La Paz County in western Arizona. He quickly figured out this is because La Paz County split off from Yuma County in 1983. It is not because there are no dockets for mines and prospects in La Paz County. Some mines for which there are dockets, such as the Three Musketeers tungsten mine, are now in La Paz County but were in Yuma County when the USGS mineral resource programs were in effect, from 1950 to 1974.
You have to search for La Paz County mines in the Yuma County listings.