Americans have a reputation overseas for being somewhat insular in their knowledge about other nations, societies and religions. Whether this is deserved or not is a moot point. But I think it would be a fair comment to say that until the Vietnam War began for example, most Americans didn’t even know where it was.
I suspect the same holds for Islam. Obviously it wasn’t highly visible in the US until 9/11. There was the occasional hiccup before that eg. Cassius Clay changing his name to Muhammed Ali. But such events were isolated enough that they didn’t impinge on the national consciousness, and posed no threat to anybody. 9/11 changed all that, even though the US has been very heavily engaged in the Middle East ever since the development of modern oil based industry, and particularly with the re-establishment of Israel. With the Soviet invasion of Afghanistan, the US was heavily involved with Pakistan in fomenting Islamic opposition to the Soviets. In fact, to some extent, you’re reaping the result of that involvment right now. Even before that, for some reason, the US never seemed to trust India, and helped Pakistan there as well.
In the case of home-grown Black Moslems, I think it’s more of a protest than anything else against the way they’ve been treated.
One thing is for sure - Islam isn’t going away, and it’s going to impinge more and more on the West.