Most folks don't have but a few days to a week's worth of food in their houses at any given time. When they run out, they'll have to forage. Only the fools will forage in town. The smart ones will look on the outskirts.

That’s the thing about the collapse of civilization, Blake. It never happens according to plan – there’s no slavering horde of zombies. No actinic flash of thermonuclear war. No Earth-shuddering asteroid. The end comes in unforeseen ways; the stock market collapses, and then the banks, and then there is no food in the supermarkets, or the communications system goes down completely and inevitably, and previously amiable co-workers find themselves wrestling over the last remaining cookie that someone brought in before all the madness began.