Like many other federal holidays, Martin Luther King Day has multiple meanings: a day to reflect on the slain civil rights leader's life, a day off from school and work, or a day to catch up on some homework.

Every third Monday of January, schools, federal offices, post offices and banks across America close to honor King's legacy of peaceful protest and social activism (his actual birthday is January 15).

This Monday marks the 18th time Dr. Martin Luther King Jr.'s birthday will be observed as a U.S. federal holiday.

From birthday to holiday

Just four days after King was assassinated in 1968, Rep. John Conyers (D-Mich) submitted legislation proposing to make the civil rights leader's birthday an official holiday. It took nearly 20 years of lobbying politicians and gathering public support before it received full backing from Congress. And even then, many cities were reluctant to observe it.

Martin Luther King Day was officially observed for the first time in 1986, becoming the first new federal holiday since Memorial Day in 1948.

The holiday sparks controversy from time to time. For example, a school superintendent in Richmond, Virginia withstood some criticism in recent weeks when he decided to keep the schools open on the King holiday to make up for a snow day. Yet for many observers the day provides a chance to reflect on King's beliefs in nonviolence and civil rights for all.

"Dr. King was well ahead of his time," Joseph Lowery, who marched with King during the Civil Rights Movement, said. "Even those very much opposed to him during his lifetime have come to see that segregation, injustice and militarism are concerns which must be addressed by modern society."

A day on, not a day off

King's widow, Coretta Scott King, says that the day was always intended as a one of activism that mirrored her husband's life during the Civil Rights movement, rather than just an empty celebration.

"Every King holiday has been a national 'teach in' on the values of nonviolence, including unconditional love, tolerance, forgiveness and reconciliation, which are so desperately-needed to unify America," Mrs. King said. "The day is above all a day of service."

Some cities have taken that to heart and called on residents to observe the holiday as "a day on, not a day off." Trumpeting the words of King, who once said, "Life's most persistent and nagging question is 'What are you doing for others?'," officials decided to use the day as a backdrop for volunteering.

In 1994, former Pennsylvania U.S. Sen. Harris Wofford and Atlanta Congressman John Lewis co-authored the King Holiday and Service Act in 1994 to encourage people to volunteer on that day. Former President Bill Clinton signed it into law.

Two years after its passage, more than 1,000 volunteers in Philadelphia painted schools and cleaned up trash-strewn parks. Since then the movement has grown. Last year, 30,000 volunteers in the Philadelphia area and in New Jersey beautified local schools, delivered food to the elderly, and collected and packaged supplies to Afghan refugees.

The King legacy

Other cities have used the holiday as an opportunity to spark open discussion on race relations in the U.S. In Austin, Texas, a group called the Heritage Council joined other cities with marches and rallies that 20,000 people attended, but it also sponsored a dialogue on race with regular citizens.

Plans to build a national monument for King in Washington, D.C. are also underway. The four-acre site has already been approved and the Martin Luther King Jr. National Memorial Project Foundation, Inc, formed by King's college fraternity, Alpha Phi Alpha, is now raising funds for the project.

-- By Raven Tyler, NewsHour Extra