This seems very interesting. 
What is the timeframe here - how long after the fog arrived is this situated? What about more primitive weapons like bows, spears, etc. - would those be useful, or completely outshined by guns? The fog comes and goes to places, or is it a permanent thing in some areas? What about normal animals, are there some still left in the wild, or were all killed/mutated by the fog?
Also, I am not from US, and I have a rather rough idea where Seattle and Pennsylvania are located. But according to googlemaps there is over 2600 miles between the two places. I assume the plan isnt the walk the entire distance on foot, so there are some vehicles still operational?