Move to the west coast, but not in any major city. If the US gets nuked, the fallout will spread east and contaminate everything to the East, therefore go West. Unfortunately the west is pretty arid, and you need to be in NoCal to PNW. Anything to the south is too dry and anything east is too contaminated. Really your best bet is to do some sea-steading on the west coast. This also fixes you need for a running land vehicle. Then get South of the Equator, unless SA , Africa or Australia get hit too. The radiation interchange from north/south hemisphere is not that strong. Eventually it will happen, but it'll be weakened. As for land lubbers, any metallic building with a grounded floor (think metal or metal screen) should be fine. Multiple layers (outer housing, so a screen would help stress on the NP junctions). Don't forget your electronics are in a metal body too. You could just keep your electronic components in a separate place. A backup alternator, dist, ECU, won't run that much, all under $200. Plus you have spares This has the advantage of taking up a much smaller space and being portable, unlike a metal shed. Check out the old movie "Panic in the Year Zero" to see how it would all go down.