What happened 21 December in United States of America

On December 20, 1860, South Carolina took the lead by adopting an ordinance of secession.

By 1934, Disney had become dissatisfied with producing formulaic cartoon shorts, and believed a feature-length cartoon would be more profitable. The studio began the four-year production of Snow White and the Seven Dwarfs, based on the fairy tale. Snow White premiered in December 1937 to high praise from critics and audiences. The film became the most successful motion picture of 1938 and by May 1939 its total gross of $6.5 million made it the most successful sound film made to that date. Disney won another Honorary Academy Award, which consisted of one full-sized and seven miniature Oscar statuettes. The success of Snow White heralded one of the most productive eras for the studio; the Walt Disney Family Museum calls the following years "the 'Golden Age of Animation' ".

The Sino-American Mutual Defense Treaty with the Republic of China was signed in December 1954.

On November 19, he announced on his website that Relapse: Refill would be released on December 21. The album was a re-release of Relapse with seven bonus tracks, including "Forever" and "Taking My Ball".

In December 2013, The Washington Post revealed a covert CIA program, started in the early 2000s, which provides the Colombian government with intelligence and GPS guidance systems for smart bombs.

The company announced on December 21, 2017, that John Schnatter would step down as CEO of Papa John's Pizza on January 1, 2018, to be replaced as CEO by current company President Steve Ritchie with Schnatter remaining chairman at the time.