I hope its strictly an American fantasy to think you're driving out of anywhere when something like that happens.
Buy a bicycle.
Buy a bicycle.
https://www.nj.com/news/2012/11/sandy_gas_ration_12_counties...
But I bet there would be a lot of bicycle and vehicle theft going on, in such an event.
And we do have all kinds of disasters, but the state not only effectively intervenes, but also supports the aftermath and reconstruction. In America there are some crazy examples of towns just being left straight out abandoned afterwards, because tehre's no such thing as government reconstruction support.