Air pollution, development, and funding cuts are just some of the problems facing the U.S. national parks system, according to the National Parks Conservation Association’s annual report on the country’s 10 most endangered parks. The diversion of water from the Rio Grande and air pollution from Mexico are threatening Big Bend National Park in Texas, the group says. Pollution from power plants is affecting air quality in the Great Smokies, and coastal development and a proposed oil-drilling project are threatening the Everglades. The report goes on to describe how motorized transportation in all of its manifold forms is putting other natural areas at risk. Consider, for example, highway construction in Georgia’s Ocmulgee National Monument, increased cruise ship traffic in Alaska’s Glacier Bay National Monument, and, of course, snowmobiles in Yellowstone. Other threatened areas cited by the NPCA include Montana’s Glacier National Park and the Mojave National Preserve. (Sorry, tortoises).