Explain the causes of the public reaction associated with the red scare

Fallout Lore!!, just kidding. The US became very patriotic but was also constantly worried about the threat of total atomic annihilation. This caused many somewhat wealthy people to build actual fallout shelters in their backyards, especially during the fifties and sixties. Other than people almost constantly worrying about the cold war going hot, I can't think of much more going on at least in the US