Martin Luther King Jr. Day, a federal holiday designated as a national day of service to encourage all Americans to volunteer and improve their communities, according to the National Museum of African American History and Culture.

It was first proposed four days after King's 1968 assassination outside a Memphis motel. It took 15 years until it became a federal holiday.

Federal and state offices, banks, as well as postal and trash services will be closed or suspended Monday. Here’s what else you should know.