The continental United States was out of reach of enemy bombers. However, when the war began, there was concern that Japan could established bases close enough to reach the U.S. We had air raid warnings. I was just a child but I remember them. We had black out curtains on our school auditorium windows.
If our country was ever attacked the U.S.Constitution allows the military to commandeer from private citizens their property they felt would help our national defense , including their homes their automobiles or whatever. Our national defense at that time would take priority over everything.
I know one man who said when he was first inducted at the start of the war was told anytime they had to do that and they met resistance to be prepared to shoot. They were definitely concerned of Japanese attack and a Japanese invasion.
There has been an argument because of that that our civil liberties can be suspended while we have been at war in Afghanistan and Iraq. The argument on the other side is that the war we have been fighting is not an officially declared war by Congress. Actually none of the wars we have fought since WW2 have been officially declared war, but anytime we get into a war that is officially declared by Congress the Constitution can give the government grounds to suspend our civil liberties.