I understand that you have to submit a copy of your blue prints with the Building Permits Office in order to build a house, but is there a way to hide a "safe room" on these blue prints? Can't the government simply look up your house blue prints that they will have on file and bring them when they start searching homes for "excess" food storage or guns during a National Emergency?
Not all counties require the submission of a set of prints for your home, but if they do, there are several options available to "disguise" your secure room.
You could always re-label it as "unfinished bsmt", "wood storage", or simply don't add it on until after you have recieved your certificate of occupancy, and all inspections are complete. The advantage of we have right now is that few local government officials are "looking" for these kind of rooms during their plan reviews. However, if you plan on taking a public stand about your political views, make sure your plans don't give any clues--they may be scrutinized.