There are three ways to consider this question - three ways it could be rephrased: how anti-Jewish was America? There has always been an element of anti-Semitisms in the US. Intuitively, I suspect that it was on the decline after WWII and perhaps there are some statistics that address that, but asking the question about anti-Semitism is the first way to frame your question.

The second way to ask the question is the way you presented it - how anti-Israel was the US. The US has long had a unique relationship with Israel, and pro-Israeli sentiment has been a dominant part of the US persona. Obviously anything of this sort of going to rank higher or lower in polling. As the Palestinian question was exacerbated after the '67 war with the annexation of the West Bank and Gaza, many Americans faced a moral dilemma: supporting Israel (an obvious thing to do for many if not most in the wake of the Holocaust) was challenged by an instinct for fairness (that is whether the wish to see Jews with a homeland should necessarily deprive people living on that land from having a homeland or from being treated with dignity and fairness).

And this leads to the third way that this question could be asked, namely, how anti-Zionist was the US before 1997. The question of the potential excess of Zionism created expressions of discontent in the US - even for those supportive of Israel. It would probably be best to separate the questions of attitudes toward Israel and of those toward Zionism: it is possible to support the one without supporting the other. An interesting question might be regarding whether there was an increasing number of people who were anti-Zionist while also being pro-Israel. Of course that could imply that these people understood the subtle distinction that separated the two.

A good expression of the widespread concern about the consequences of Zionism can be seen in the case of Vanessa Redgrave and her support for the 1977 documentary The Palestinian. The theater where the film was to premiere was bombed, delaying its opening until the following evening: clearly someone was more pro-Zionism than pro-Palestinian! There was considerable opposition to the film and its sympathetic portrayal of the plight of the Palestinian people. This came into play with an effort to deprive Redgrave of the 1978 Oscar for her commanding performance in the film "Julia", which ironically was about someone who struggled to fight the Nazis in pre WWII Germany. Redgrave won the Oscar and used the opportunity to speak out on behalf of Palestinians. Her speech was greeted with boos and was not well-received. Sentiments were clearly split and at least in the Oscar auditorium, the pro-Israel element was louder than any anti-Zionist there. Nevertheless, Redgrave was giving voice to a point of view that has been part of the complex of American attitudes, especially since 1967, when it comes to Jews, Israel, and the Palestinian question.