What events and figures have shaped the development of Islam in the United States?

That is entirely too broad. Some info may be found here:

Islam in the United States - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Islam_in_the_United_States)

The answer you may be looking for could be the 911 twin tower incident, which was an eye opener to some in finding the true Islam to be very different from what the media portray and what a few muslims actions prove.