Adult animation in the United States

In the United States, before the enforcement of the Hays Code, some cartoon shorts contained humor that was aimed at adult audience members rather than children. Following the introduction of the Motion Picture Association of America film rating system, independent animation producers attempted to establish an alternative to mainstream animation, as such led to the most successful work is Ralph Bakshi's Fritz the Cat.

Source: Wikipedia — Adult animation in the United States (CC BY-SA 4.0)