- Tectonically sound
- Far enough inland for any epic tsunami.
- Enough elevation - just handy in general
- West of the Yellowstone super volcano's eruption and fallout
- Low population density
- Resources: national forest with rivers for water, hunting, and fishing
- Lack of major highways and interstate - keeps the likelihood of outsiders low
That's just off the top of my head. I'm no prepper. I don't even have a flashlight.