The 1970s witnessed a groundswell in memorable horror movies. The MPAA ratings system opened the doors for more explicit content, which producers took full advantage of. The critical success of Rosemary's Baby in 1968 provided artistic legitimacy to the genre, and while the decade saw its share of dreadful schlock, it also produced some of the greatest horror films of all time, including Halloween, Carrie, and The Exorcist.
Source：https://www.cbr.com/underrated-70s-horror-movies/
