An invasion of the US in 1942–1943 by Nazi Germany was entirely out of the question. Even if Britain had surrendered right after France did, the Germans were not prepared to mount a trans-Atlantic invasion, and had no plans to do so.
I guess if you posit a miraculous timeline it might be possible in 1943, if it looked a bit like this:
1940: France and Britain surrender.
1941: Germany invades Russia earlier in the year than it did, weather cooperates much more than it did historically. Germany captures Moscow and Stalin, Russia surrenders.
1942: Germany builds up infrastructure and equipment, and takes over the entirety of the French and British navies. Japan does not start war with the USA, who do not start war mobilization.
1943: Japan and Germany both attack the USA. With no other fronts to worry about, and all the military and civilian ships from France, England, Germany and Italy, they actually have some way of conducting an invasion and supplying it.
That last detail is one of the main reasons why not. With only German ships, there was no way to conduct an invasion and keep it supplied. Even so, I’m not sure it would be logistically possible because of the enormous sea distance. The only way the USA was able to invade Nazi-occupied France was by stockpiling men and supplies at logistics bases in Britain for months before the invasion.