The Crucible is allegorical because of the false accusation without regard of evidence. Senator McCarthy accused people of being communists without evidence. The fear of communists taking over could be connected to the fear of being accused of witch craft.
A student from New Hampshire has compared McCarthy to Donald trump by connecting the fear of communism to the fear of Muslims. "Today, Americans appear to be embarking on a similar witch-hunt fueled by fear — this time instead of hunting for communists and spies, Americans are hunting Muslims." McCarthy had brainwashed America with the fear of communism being closer than they appear, Trump has convinced America that Muslims and Mexicans are terrorists.
http://www.huffingtonpost.com/kendall-pope/donald-trump-a-modern-day_b_9583702.html - Link for article connecting Trump with McCarthy