300 million people and 4 million square miles.
There won’t be enough personnel to even impose martial law on the cities. Which can be expected to burn, and burn quickly.
How many troops did it take, and how fast, to lock down Boston?
And you don’t have to work hard to impose your will on a population of sheep, like there was in Boston. They willingly accepted troops on the street, and stormtroopers in their homes.
You just have to tell them that “Those Evil Racist Teabaggers” are nearby, and they’ll turn in their neighbors for EBT cards that work.