LEARN MORE: Individual park initiatives

In 1968, a policy of controlled burns was initiated in Sequoia National Park after it was discovered that years of safeguarding the trees from fire had stopped their reproduction. The NPS also put a stop to the "firefall" tradition at Yosemite National Park, a nightly event during the summers at which a bonfire of burning embers was poured over the edge of Glacier Point. The crowds that gathered to watch the show left behind trash and trampled plants. At Yellowstone, another nightly practice of allowing crowds to watch as bears fed on garbage was ended, reducing the bears' exposure to humans and, in turn, the human injuries and property damage caused by bears each year.