I've hiked some pretty rugged back country trails in both Yellowstone and Yosemite. Even the "well traveled" so-called "easy" trails can be dangerous. The Mist trail in Yosemite for example is a really easy trail, but if the rocks are wet you can slip, fall in the river, perhaps hit your head or get carried away with the current if the river is flowing strong in the spring.
One observation I've made is that most people visiting the national parks are tourists. That's not bad, it just is. And as such they really don't understand that they are in a wilderness and not another Six Flags park. I've seen people trying to push strollers on hiking trails, wearing flip flops, not carrying anything other than a camera (no water!), kids running amok, etc.
I've seen people getting chased by elk. I've seen them go right up to a buffalo. I've seen them hang off of parapets to try and get photos. It's a wonder there are so few deaths.
ddndoug wrote:
Maybe a silly question, but... I've not yet made it to Yellowstone, are the trails that close to cliffs that a simple misstep or "loss of footing" could send a person tumbling to their death?
Oakman posted a nice photo above, but yes, many of the trails in the national parks can be dangerous. In Yellowstone there are warning signs all over the place about not wandering off the trails because of all the hot springs and thin crust that can break through if you step on it.