The size of the crowd gathered on the Mall in Washington, D.C., 50 years ago today was staggering, but it was not the event’s epic feature.

It was the fact that 250,000 people from different races, different cultures, different worlds gathered peacefully, respectfully and attentively.

It was that fact that a black preacher, during a time of widespread racial violence, distrust, anger and fear, delivered a speech that mesmerized and moved white people and black, old people and young, Jews, Christians and the unchurched.

It was Martin Luther King Jr.’s vision of a peaceful, kind, fair and respectful world — a vision that all who were there could embrace.

And it was an iconic example of humanity at its tolerant, hopeful, moral best.

Much larger crowds have since gathered. Over 5 million people attended a World Youth Day rally in Manila in 1995 to see Pope John Paul II.

An estimated 4.2 million people attended a concert given by Rod Stewart in Rio de Janeiro in 1996.

An estimated 3 million people attended a parade in Boston to celebrate the Boston Red Sox’ 2004 World Series.

But the march that culminated at the steps of the Lincoln Memorial didn’t have the advantage of being like-minded people happy with their opportunity to see the pope/hear Rod Stewart/cheer their favorite team.

Some expected things at the Mall to be testy, if not rough. Marches, sit-ins and walk-outs protesting segregation had proven tense — sometimes the response was ugly and violent.

Indeed, a total of 5,900 police officers, 2,000 National Guardsmen and 4,000 soldiers were on duty.

Even civil rights activists were at odds. Some were worried the march would turn violent and some predicted it would have no real effect. Both were proved wrong.

Martin Luther King’s words distinguished this march from all others. His dream was a unifying one, where his children — all children? — would “not be judged by the color of their skin but by the content of their character.”

His warning against bitterness and against physical violence was both a comfort and a challenge.

And his words continue to inspire 50 years later. Schoolchildren are often required to memorize Abraham Lincoln’s Gettysburg Address. And many adults remember those powerful words as a symbol of a dramatic chapter in our country’s history.

But children and adults alike can quote parts of Martin Luther King’s speech, not as a history lesson but as a message that is as instructive today as it was on Aug. 28, 1963.

People can reasonably disagree about the state of race relations in the country 50 years after the march. But there is no question that things have greatly improved. And certainly there is more that needs to be done.

In South Carolina, for example, legislators should revisit the 13-year-old compromise that brought the Confederate flag down from the Statehouse dome to a more visually prominent location on the Statehouse grounds.

The flag continues to be a flashpoint of controversy, and in the spirit of comity, the Legislature should seek a more agreeable resolution over its placement.

Certainly all Americans should agree with the uplifting, unifying sentiments expressed by Martin Luther King Jr. a half century ago.

His epic “I Have a Dream” speech, and the spectacle of the 250,000 people who heard him that day on the Mall, together remain a lodestar for the country as it continues its quest for human rights.