. >> repr: kevin dahl works with the national parks conservation association. he says being a cactus thief can be lucrative: each one can fetr $100re per foot. >> it's absolute robbery and it's absole criminal activity and it's for profit a mature saaro in a landscape. add something to the value of the home or the business that's for sale or rent. >> reporter: across the country, other parks are facing a similar threat. last year, death valley national park says some visitors walked off with fossil footprints. at joshua tr national park, people have stolen artifacts from old mines. >> some parks deal with people taking rocks, some parks deal with people taking plants and animals. places like mount rushmore people take the chips that were created when they created the sculptures. >> reporter: bill parker leads the natural and cultural resources team at petrified forest national park. here, he says, visitors take small pieces of petrified wood. >> some people do still take awood and we catch th give them tickets. but whole areas are stripped clean as was thought

and kevin dahl wants to make sure that visitors understand the national parks are saved by the people for the people. >> it's a selfish thing when when someone does an act of vandalism or steal something from a national park and it's selfish and it's an act against the american public. ri>> reporter: pieces of an history being taken from some of amera's most treasured land. for the pbs newshour, i'm tyler fingert at sagauro national park in arizona. oodruff: on the newshour online right now, find ideas for how to help guatemala after the deadly volcanic eruption there. that and more is on our web site, pbs.org/wshour. and that's the newshour for tonight. i'm judy woodruff. for all of us at the pbs newshour, thank you anyou soon. >> major funding for the pbs newshour has been provided by: >> the ford foundation. working with visionaries on thf frontlines ocial change worldwide. >> carnegie corporation of new york. supporting innovations in education, democratic engagement, and the advancement of international peace and curity. at carnegie.org. >> and with the ongoing support of these i