Monday marks Martin Luther King Jr. Day, the federal holiday that honors the life and legacy of the American civil rights icon who was assassinated in 1968. The holiday is observed each year on the third Monday of January, and the commemoration is the only federal holiday that is "designated as a national day of service to encourage all Americans to volunteer and improve their communities," according to the Smithsonian National Museum of African American History and Culture. But the holiday didn’t come together seamlessly. Efforts from King’s widow, Coretta Scott King, lawmakers, activists and others took years. Tap the link in bio to learn more about how Martin Luther King Jr. Day became a holiday. #martinlutherking #martinlutherkingday