AJO, AZ - MARCH 27: An abandoned vehicle illegally driven across the international border at the Cabeza Prieta National Wildlife Reserve with four flat tires is seen on March 27, 2006 near Ajo, Arizona. Escalating environmental problems associated with the region's massive illegal immigration into the USA from Mexico and stepped up border enforcement efforts in the vast and desert wilderness in and around the Reserve and Organ Pipe National Monument, it has been described as the nation's most embattled wilderness by reserve officials. Discarded trash is accelerating widespread off-road vehicle damage on the fragile Sonoran Desert plain at an unprecedented rate. (Photo by David McNew/Getty Images)