On March 21, 1965, Martin Luther King, Jr. began his third march from Selma to Montgomery, Alabama to protest racial discrimination in the Jim Crow South. By March 25, over 25,000 people lead by Dr. King reached Montgomery, Alabama. Specifically, the march called attention to suppression of African-American voting rights and a police assault on a civil rights demonstration three weeks prior.

Five months later, in August 1965, Congress passed the Voting Rights Act. Read a history of the march from Selma to Montgomery and a history of the Voting Rights Act.

March 21 is the International Day for the Elimination of Racial Discrimination [UNESCO factsheet].
On March 21, 1804, the Code Civil des Francais, the reformed French civil law often referred to in French as the Code Napoleon, and in English as the Napoleonic Code, went into effect in France, Belgium, Luxembourg, and French colonies.