Rangers have conducted about 90 search and rescue operations Yellowstone and Grand Teton national parks so far this year.
Yellowstone spokesman Al Nash says an estimated 15 "major" and 20 "minor" search and rescue operations have occurred in Yellowstone, which covers parts of Wyoming, Idaho and Montana.
A search and rescue operation involving emergency personnel is considered to be major when expenses exceed $500. Otherwise the event is considered minor.
In neighboring Grand Teton National Park, spokeswoman Jackie Skaggs says there have been 31 major and 23 minor search and rescue operations.
The Jackson Hole News & Guide reports that Yellowstone averages about 50 to 55 search and rescues annually, while Grand Teton records about 65 to 70.
Information from: Jackson Hole (Wyo.) News And Guide, http://www.jhnewsandguide.com