Since the 1950s, the Saturday morning time slot has been considered prime airing hours for kid-friendly television programming. While most of that particular decade's most successful kids' programming consisted of black-and-white action series and variety shows, the '60s saw the rise of Saturday morning cartoons as a staple of both North American television scheduling and pop culture as a whole. However, not all Saturday morning cartoons became popular.
Source：https://www.cbr.com/unexpected-weird-series-saturday-morning-cartoons/
