Was there resistance during to WWII in America once the war began?Specifically, during the war was there resistence (domestic) to the war? It...

I have never read anything about any serious opposition to
this war in the United States (not once Pearl Harbor was attacked).  You are right to
say that this was a very popular war.

The only resistance
(if you can call it that) that I have ever heard of came from some pacifist groups like
the Quakers.  These people were not really so much opposed to this war in particular as
they were to all wars in general.  These people were not very numerous and were pretty
much looked down upon by the majority of Americans.  The pbs.org link has some stuff
about these people.

But in terms of an actual movement
arguing that the US should not be in the war or anything like that, there was
nothing.