Check out the HathiTrust website at your own peril because if you're interested in government documents then you may find yourself sucked in.
Take this 1954 State Department document on relations with Latin America (Partners: The Story of Our Latin American Relations). The best quote is on the "Communist menace" in Guatemala, referring to how "the Guatemalan people themselves rose up and turned out the Communist conspirators."
That actually got me thinking about what the most egregious cases of U.S. government lying about Latin America might be. It would be a perversely interesting research project.