When the screen cartoonists’ guild formed in the late 1930s, animated shows weren’t scripted and instead were drawn out on storyboards. Because that was considered part of the animation process itself, the writers were placed under the jurisdiction of the cartoonists’ guild, said Tom Sito, a USC film professor and former president of the Animation Guild, IATSE Local 839. That dynamic has more or less continued to this day, even though today’s cartoons involve plenty of scripting.