"The struggle that the holiday itself has is to not just be a day off," Brinkley said. "We have trouble with that. We have to constantly be vigilant not to let that happen."
Legislation calling for a federal King holiday was introduced in Congress by Rep. John Conyers of Michigan just four days after King's April 4, 1968, assassination. Later that same year, Coretta Scott King, his widow, started The Martin Luther King Center for Nonviolent Social Change in the basement of the couple's Atlanta home.
She was also committed early on to Conyers' proposal — an ironic tribute to a man who usually didn't make much of his birthday. It would be another 15 years before Congress warmed to the idea and passed it into law.
President Ronald Reagan signed the bill establishing the third Monday in January as the Martin Luther King National Holiday on Nov. 3, 1983, and the first observance was Jan. 20, 1986. That year, 17 states also had official King holidays, including Illinois, which recognized King with a holiday in 1973, the first state to do so.
Arizona established, then rescinded, a King holiday in the 1980s, but finally joined the federal observance in 1992. New Hampshire was the last state to honor King, in 1999.
Today, the King holiday also is observed in more than 100 countries, according to The King Center.
In 1994, the meaning of the holiday shifted as Coretta Scott King called for less of an emphasis on his life and more of a focus on his legacy. The mission was expanded to include volunteerism, interracial cooperation and youth anti-violence initiatives.
More than a million Americans are expected to participate in 13,000 projects around the country on the King Day of Service, said Patrick Corvington, head of the Corporation for National and Community Service, the federal agency charged with administering service projects on the King holiday. The focus on service makes the holiday more inclusive, Corvington said.
Corporate America has been slower to respond. A survey of 300 businesses by the Bureau of National Affairs showed three in 10 will give all or most of their workers a paid holiday on Monday. The legal and business publisher reports the figure is a significant increase over the first 11 years of the federal holiday observance.
According to the BNA survey, only 14 percent of surveyed businesses made the King Day a paid holiday in 1986, and figures stayed in the teens until a 1993, when the number rose to 24 percent. Since 2003, the number has hovered around 30 percent of employers.
- Photo gallery: Christmas around the world
- Officer kills armed 18-year-old near Ferguson
- NORAD 'tracks' Santa's journey across globe
- Our six heroes of 2014
- Ex-President George H.W. Bush to stay...
- Final goodbye: A roll call of some who died...
- On Christmas, Obama marks end of Afghan combat
- Capacity crowds pack screenings of 'The...
- NYPD: Cop ambush killer told passers-by... 15
- Going it alone, Obama rocked the boat... 13
- Officer kills armed 18-year-old near... 10
- Pope in blistering critique of Vatican... 9
- Key developments in the case of slain... 9
- Killings of 2 New York officers trigger... 6
- Senate, CIA agree torture program was... 6
- Sony announces limited release for 'The... 5