Short answers, pulled from the story.
Saturday-morning cartoons as an organized programming block on the Big Three networks ran broadly from the mid-1960s to the mid-2010s. The last non-educational cartoon block on a major American network closed on the 27th of September 2014, when The CW ended its Vortexx block.
The decline resulted from several overlapping pressures: competition from cable channels like Nickelodeon and Cartoon Network, educational and informational (E/I) content mandates from the FCC, restrictions on advertising during children's programming, and broader cultural shifts including the end of the post-World War II baby boom. Networks increasingly replaced animated blocks with news programs and live-action documentary shows that were easier to schedule alongside newscasts and faced fewer advertising restrictions.
In the 1960s, the price per half-hour Saturday-morning cartoon episode ranged from $48,000 to $62,000. CBS and ABC typically ordered batches of 16 episodes, while NBC ordered 13-episode batches.
Fred Silverman, as head of CBS daytime programming, reorganized the Saturday-morning block in the 1966-67 television season around four and a half hours of back-to-back animated series, pushing CBS to first place in the ratings. He later disputed claims that the Action for Children's Television and parental lobbying were the primary reasons action cartoons declined, arguing instead that ratings for superhero series had already begun slipping by the late 1960s.
By December 1998, the Pokémon anime was the highest-rated syndicated children's show on weekdays, triggering a bidding war between Warner Bros. and Saban Entertainment/Fox Family Worldwide. Warner Bros. won, and Pokémon launched on Kids' WB on the 13th of February 1999, setting a viewership record for that block's premieres. Its success prompted other blocks to acquire competing anime titles and displaced established series, including The Avengers: United They Stand, to make room.
As of 2026, Univision and MeTV are the only commercial broadcast networks still airing animated programming in a Saturday-morning timeslot, through their Planeta U and Saturday Morning Cartoons blocks respectively. Weigel Broadcasting also launched MeTV Toons, a 24/7 classic animation network, on the 25th of June 2024 in partnership with Warner Bros. Discovery.