Time Magazine has a short but informative article on the lengthy work that went into getting Martin Luther King Day passed as a national holiday:
“This is not a black holiday; it is a peoples’ holiday,” said Coretta Scott King after President Ronald Reagan signed the King Holiday Bill into law on November 2, 1983. Fifteen years prior, on April 4, 1968, she had lost her husband, the Rev. Martin Luther King Jr. to an assassin’s gun. In the months after the civil rights icon’s death, Congressman John Conyers Jr. of Michigan introduced the first legislation seeking to make King’s birthday, January 15, a federal holiday. The King Memorial Center in Atlanta was founded around the same time, and it sponsored the first annual observance of his birthday in January 1969, almost a decade and a half before it became an official government-sanctioned holiday in 1983. Before then, individual states such as Illinois, Massachusetts and Connecticut had passed their own bills celebrating the occasion.
The origins of the holiday are mired in racism, politics and conspiracy. Three years after Rep. Conyers introduced preliminary legislation in 1968, the Southern Christian Leadership Conference — which King headed from its inception until his death — presented Congress with a petition of 3 million signatures supporting a King holiday. The bill languished in Congress for eight years, unable to shore up enough support until President Jimmy Carter, former Governor of Georgia and the first Democratic president since Lyndon Johnson, vowed to support a King holiday.