AIDS almost certainly spread to the USA from Haiti, where it had incubated and proliferated enormously amongst the Port au Prince prostitutes, but it most likely originated on the African mainland over a century ago (some 40 years or so before the CIA was founded). The following timeline seems plausible and obviously the bushmeat / "cut hunter" scenario is somewhat more palatable than the cross-breeding one.
Thought it was pretty well established that it was spread through bushmeat and had probably existed at a low level in local populations in Africa for a long time. I seem to recall that the possible patient zero in terms of infecting the US ha£ been identified as a sailor in the 50s? But it’s possible I’m confused on that.