Jim:
In How to Survive the End of the World as We Know It, you missed mentioning one of the great uses of "bypassed areas" -- that of an en route cache. There is no question but that it would be plain stupid for any family to wait to leave the big cities and urban areas until the very last moment when TSHTF, urban riots have broken out, and the freeways have become one big parking lot full of shooting and looting. But many families will want to hang on in the cities as long as possible because of employment, family commitments for the care of elderly relatives, and other reasons. When they do leave, it would be much safer for them to quickly exit along the back roads with only the clothes on their backs and half a tank of gas than to take the time to stuff their vehicle full of survival goods and become a visible target of great interest to looters along the road.