These pinback were issued to promote January 15 as the national holiday for Martin Luther King, Jr. Though President Ronald Reagan signed the holiday into law in 1983, it was first observed three years later. At first, some states resisted observing the holiday as such, giving it alternative names or combining it with other holidays. It was officially observed in all 50 states for the first time in 2000….
After King’s death, United States Representative John Conyers (a Democrat from Michigan) and United States Senator Edward Brooke (a Republican from Massachusetts) introduced a bill in Congress to make King’s birthday a national holiday. The bill first came to a vote in the U.S. House of Representatives in 1979. However, it fell five votes short of the number needed for passage. Two of the main arguments mentioned by opponents were that a paid holiday for federal employees would be too expensive, and that a holiday to honor a private citizen would be contrary to longstanding tradition (King had never held public office). Only two other people have national holidays in the United States honoring them: George Washington and Christopher Columbus.
Soon after, the King Center turned to support from the corporate community and the general public. The success of this strategy was cemented when musician Stevie Wonder released the single “Happy Birthday” to popularize the campaign in 1980 and hosted the Rally for Peace Press Conference in 1981. Six million signatures were collected for a petition to Congress to pass the law, termed by a 2006 article in The Nation as “the largest petition in favor of an issue in U.S. history.”
Civil Rights Heritage Museum Online 