Good question Brangdon, I hadn't taken the "opportunity cost" of interest into account, nor had I taken inflation into account. How much is needed? Perhaps some folks who lived through the aftermath of Katrina can help us out? How much did they need, and for how long did they need it?

There are two scenarios: bug-out, and dig-in. If I bug-out, how much will it cost for me to reach safety? A WAG to get from DC to the back-woods of Michigan over 3 days would be $1,000 (250 gas, 600 lodging, 150 food/water). So, like any good engineer, I'm going to take my wild guess and double it to $2,000. I'll offset the opportunity-costs by using my emergency fund instead of out-of-network ATMs when I need cash.

As for the dug-in situation, my brother didn't really need all that much money when the power-grid went down. He just needed enough cash to pay for his bar tab, and to top off his pantry with food and water for the week. I think my bug-out estimate of $2,000 would have worked well for him.

How much did the folks who dug-in for Katrina and then had to rebuild need? That's the real question. MrDrysdale mentioned that his credit union limited people to $500 of their own cash, and that would not last long in an emergency. Assume we have access to that cash, would an extra $2,000 in bug-out money be sufficient to rebuild? What costs were there, and how long was the cash needed?