Brendan Smialowski/Getty Images

Visitors today commemorated the Rev. Martin Luther King Jr. at his memorial on the National Mall in Washington, D.C., marking the first holiday at the site, which opened in August.

The King Center today also posted about 200,000 never-before-seen documents by the slain civil rights leader on its Web site. The documents are wide ranging and give a closer look into the portfolio of  one of the world's most revered civil rights leaders. The online archive contains materials such as King's transcript from Harvard University, his personal notes, telegrams to President John F. Kennedy and letters to and from Vice President Richard Nixon.

In a letter to Nixon, King describes the need for a sustained grassroots movement, a message that resonates even today.

"It is almost my firm conviction that the full effect of the Civil Rights Bill will depend in large degree upon the program of a sustained mass movement on the part of Negroes," King wrote to Nixon Aug. 30, 1957. "History has demonstrated that inadequate legislation supported by mass action can accomplish more than adequate legislation which remains unenforced for the lack of a determined mass movement."

The archives released today also include such personal notes as hate mail to King, calling African-Americans "savages" and accusing the Nobel Peace Prize recipient of winning the distinguished award only because he came from America.

The archives were financed and overseen by JP Morgan Chase, which built a team of more than 200 individuals for the project.

Click Here to Visit the Archives

Meanwhile, President Obama and the first family commemorated King today with a service project at a local school. "There's nobody who can't serve," the president told volunteers of the civil rights leaders' legacy, adding that volunteering is the best to mark this holiday.

Vice President Joe Biden and his wife participated in the Greater Philadelphia Martin Luther King Day of Service, one of the biggest in the nation.

"Today we are, all across America, giving meaning … to the legacy," he said. "Today, we're actually acting out, we're actually acting out, even if it's only a day. We're acting out what Dr. King talked about."

Civil rights leaders and federal officials this morning laid a wreath at King's memorial to remember the leader.

The highlight of the $120 million project, led by the King Memorial Foundation, is a 30-footl tall sculpture of King inspired by his "I have a Dream" speech.

Last week, Interior Secretary Ken Salazar gave the National Park Service a 30-day deadline to fix an inscription that shortens one of the civil rights leaders' sayings.

The inscription now reads: "I was a drum major for justice, peace and righteousness."

But King instead said: "Yes, if you want to say that I was a drum major, say that I was a drum major for justice. Say that I was a drum major for peace. I was a drum major for righteousness." The quote is from a sermon titled "The Drum Major Instinct" that 39-year-old King delivered two months before he was killed, discussing how he would want to be remembered.

Poet and civil rights activist Maya Angelou, a leading critic of the paraphrasing, has said that the out-of-context quote makes King sound like "an arrogant twit."

"He had no arrogance at all. He had a humility that comes from deep inside," she told the Washington Post last year. "The 'if' clause that is left out is salient. Leaving it out changes the meaning completely."

Here is a look at pictures of the memorial's dedication  in October.