The Environmental Working Group says the 5,131 mining claims within 5 miles of the Phoenix-Mesa metropolitan area are threatening those cities by encroaching on them. They list Tucson with 1,741 claims within 5 miles, making Phoenix and Tucson the #2 and #3 cities with the most claims nearby. Las Vegas is #1 with 5,822 claims. The report is titled "Mining Claims Threaten Western Cities."
Their report appears to be primarily a data base of mining claims posted on a Google-Earth map of populated areas.
It's interesting that the mining claims they describe are on federal lands that are not open to be developed by cities or towns. So, the bigger impact is more likely to be urban encroachment on mineral resources and the desire of expanding communities to push mining out of their backyards.