The Wall Street Journal How Safe Is That National Park?
If you do get injured or find your campsite vandalized these days, it's getting harder to find a ranger to tell.  While visitation at national parks has climbed over 6% since 1995, the number of park rangers has declined by nearly 5%.  

National Geographic Guide to the National Parks of America
"Instead we seek to save the whole thing, the whole creeping, flying, grazing, preying, photosynthesizing, eroding, raining, erupting, evolving scene. Call it wildness, or naturalness or an ecosystem, or whatever you like, it is this entangled collection of processes that we must save."