Rock drawings, or pictographs, in a restricted area of Hueco Tanks State Historic Site near El Paso in El Paso County, Texas. The more than 200 "mask drawings" in the park -- the most in North America -- are the artistic legacy of different prehistoric peoples who, over several millennia, found water, feed, and shelter at this stone oasis in the desert. The "tanks" are geological depressions that catch rainwater, attracting animals and human settlement in the otherwise-dry high-desert surroundings. The area shown here is restricted because vandals have desecrated other such drawings with graffiti. Original image from Carol M. Highsmith’s America, Library of Congress collection.