Springfield Mass has some validity. At least as far as the government is concerned. When I worked for GSA, there was an offsite location close to there that had backup servers/storage that we'd have to go maintain.
Remember, the thread is in regards to Nuclear holocaust/appocalypse.first...
The mountains seem to be a common answer for many. My answer is "I'm not quite sure". Most who leave for the mountains to avoid conflict are simply going to find it anyhow. Others will most likely get there before you and do their best to defend their areas. In such a case, "common thoughts"...