Illegal immigration and drug running have destroyed border parklands, further threatened two species on the endangered list and led federal officials to bar visitors and campers in areas considered too dangerous to visit, according to newly released reports.

In studies of two parks that make up less than 90 miles of the Arizona-Mexico border, the U.S. Fish and Wildlife Service and National Park Service said that the areas have been ripped up with thousands of miles of unauthorized roads from vehicles that have crushed plants and animal habitat.