@TimTurner Your
post #14 ... its accounting of some few IOTL situations doesn't really answer my questions from
post # 13.
You don't really explain the by you claimed inherent "limit" of US antisemitism.
it's inherently limited due to the fact relatively (in this context, still potentially a lot in certain situations, but still, few enough that the US was unlikely to even mirror Nazi Germany) few groups in the US usually cared much about attacking, insulting, or even
thinking about Jews, relative to other demographics. The traditional Catholic vs. Protestant divide that existed in the US from the 1600s to the 1960s was probably the main conduit of bigotry in the United States (rivaled only by White vs Black), and its influence was reflected in the immigration debates in that time period. Despite the presence of active anti-semitism in some sections of society (especially WASPs), it was simply not as influential here as it was in Europe.
And if you are equating levels of anti-semitism with levels of bigotry overall (assuming that the environment in America could easily have been as anti-Semitic as Europe because reasons), you are looking at it wrong. There are many kinds of bigotry, many (most?) of them driven by fear and/or dislike towards a group's influence on the national culture and/or a group's divergence from thereof. When economic interests are added in the stew, it gets only more toxic, and even be an even more powerful factor. Hence, in New England, once a major manufacturing center, you had mostly Catholic laborers and a mostly Protestant managerial class. The former were mostly Democrats; the latter was mostly Republicans. The former had more babies so eventually the Protestants who once overwhelmingly dominated politics lost control. Henry Cabot Lodge was defeated in 1952 by Jack Kennedy, and the Rhode Island state GOP lost all its power in dramatic fashion in 1934. Yankee businessmen in New England were more bigoted against Catholics than they were against blacks, because many Catholics were class enemies, and political opponents. Old-school Democrats were more viscerally racist towards blacks than the Yankee businessmen, because they were direct competition for jobs. Neither blacks, Catholics, or Protestants usually thought all that much about Jews - and why would they?
IOTL, Anti-Semitism peaked in the 1920s. And this was not because of a truly massive surge of
base Anti-Semitism. It was due to fear of socialism - the Red Scare. Jews got tarred along with many Eastern European demographics, as a potentially communist-sympathizing bloc. The KKK carried the banner of 'protecting America'. The nature of Anti-Semitism in this era was linked to anti-communism - it wasn't focused just on Jews but on many demographics seen as "foreign". However, this didn't really last for a very long period of time. Immigration got restricted, especially from Eastern Europe. The Red Scare largely ended. Thus, Middle America didn't feel under threat. They went back to 'normalcy', wanting to avoid much worry altogether. (not that that 'normalcy' would last long)