There are over 640 million acres of federal land, mostly here in the west. Get lost in one of the national parks, and there's a good chance you'll never be found. By some estimates, at least 1600 people have gone missing on public lands, but the actual number may be much higher; the feds track the estimated numbers of grizzly bears and wolves on public lands, but they don't track missing persons.
“The first 24 hours are key,” says Robert Koester, a.k.a. Professor Rescue, author of the search and rescue guidebook Lost Person Behavior.
Heading for higher ground, according to Koester, is what a lot of lost people tend to do, possibly in hopes of getting better insight as to where they are as opposed to where they planned to be. It seems to often be an ineffective strategy, especially in rugged country where cliffs are involved. Adding to the problem is the fact that these people are usually not prepared; often they don't have a phone or other signalling device, much less other items like food, water, or a means to start a fire. Some have been known to leave wearing only running shorts and shoes - and not return.
It's a jungle out there.