global security has some interesting info on the highway system. I was told years ago, that many of the sections in the Dakotas, Montana and Wyoming were intended to service returning strategic bombers that might not have bases to return to after a nuclear exchange. Fuel, more bombs and communications facilities would have been set up for their return in these sections. Supposedly, this was the hidden agenda beyond the massive funding of the system in the 50's/

According to a USMC (ret) buddy, Korea does the same thing. Highways go from 2 lane divided to six for a couple of miles, then back to two. Improvised airfields. As for the US, at least in the Mid Atlantic, I would purposely avoid the major thoroughfares and interstates. There are quie a few choke points that will strangle traffic. This is an everyday issue around DC, worse in the summer. Get a good map(s) for your area and expected routes. Take a day and drive some of the back roads. It is amazing how much time they can save. Figure out more than one route. How do you get off Long Island, NY (or any island). 9/11 many walked across the bridges. Are the ferrys going to run? The theme here is that most people will be on the "easy routes" or those few that they routinely use. In an incident that requires evac, I want to be away from the crowds as much as possible.

Thanks for all the responses. What williamlathan says is what I do on a regular basis. I have driven all over to get to the same spot just to check out the roads. My wife gets mad every time we go to my parents because she says I never take the same route twice.