The U.S. attracted about 11% of worldwide mineral exploration projects in 2012 and of the 334 U.S. exploration projects identified by the USGS, 35% were located in Nevada, 13% in Alaska, 12% in Arizona, 7% in Idaho, 5% in Wyoming, 4% each were located in California and New Mexico, 3% in Utah, and smaller amounts in a number of other states. The annual Exploration Review was published in SME's Mining Engineering magazine. [Photo credit, Asarco]
In comparison, Arizona generated about 11% of the value of all U.S. mineral production in 2012, making Arizona the #2 state behind Nevada.
According to the article, "The U.S. nonfuel mineral exploration budget was anticipated to increase by about 23 percent to about $1.7 billion in 2012 from $1.4 billion in 2011, according to MEG data. The U.S. percentage of the world exploration budget remained at 8 percent in 2011. The increase in the U.S. minerals exploration budget in 2011 is tied to an improved economy, higher commodity prices and higher exploration costs."
Ref: Exploration Review, by D.R. Wilburn, K.A. Stanley, U.S. Geological Survey
Mining Engineering magazine, May, 2013, Pp. 32-52, http://me.smenet.org/abstract.cfm?preview=1&articleID=3424&page=32