National Geographic reports that the new barrier recently built on the U.S. border between Arizona and Mexico has been effective in eliminating illegal crossings by vehicle through Organ Pipe National Monument, but an unintended consequence in a sharp increase in foot traffic through the adjacent Cabeza Prieta National Wildlife Refuge.
Prior to the barrier's construction, large numbers of vehicles crossed over from Mexico at all hours, carrying illegal drugs and immigrants. hundreds of miles of dirt roads were cut into the desert by these unwanted vehicles, and rangers say it will take hundreds of years for them to grow over again without human intervention.
Now that vehicles cannot cross, smugglers as moving into the U.S. on foot, many of them through the wildlife refuge. Not only are they eroding the natural terrain, they are also polluting it with large amounts of trash and human feces.
The smugglers are not the only ones damaging the landscape-- law enforcement officials from the border patrol and the park and wildlife services must move through the area to deal with the interlopers, and they also erode the natural desert.
There is some good news: In 2008, Cabeza Prieta is slated to have its own barrier at the border completed. Still, good news for the wildlife refuge is bad news for some other border area, since illegal crossers will just go somewhere else.