[quote=@Apollosarcher]
[@Earnest Evans] Actually only one of the Zeppelins fell. The others made it intact.
[/quote]

This is true. However, that was the [i]main[/i] zeppelin, and it was nearly completely destroyed by one of the many storms covering Tornado alley. I'm assuming that the other Zeppelins made it through dumb luck. For people on-foot without the benefit of being above the cloud-line, I'd imagine making it across America is something doable only through a miracle.

After all, the only stuff from the East Coast that we can see in New Vegas is the Wasteland Survival Guide and some Fire Ants. This implies that [b]some[/b] people made it through, but the complete lack of anything else suggests that [b]only[/b] those people made it through.