U.S. Border Patrol agents detain a group of men on National Wildlife Refuge land outside of Sasabe, Ariz., in 2006. Environmental concerns have limited the range of patrol agents along the U.S.-Mexico border. (Associated Press)

U.S. Border Patrol agents detain a group of men on National Wildlife Refuge land outside of Sasabe, Ariz., in 2006. Environmental concerns have limited the range of patrol agents along the U.S.-Mexico border. (Associated Press)