Forty-eight years after Dr. Martin Luther King Jr.’s “I Have a Dream” speech, thousands flocked to the National Mall Sunday for the dedication of a memorial to the civil rights activist.

The memorial opened to the public in August, but organizers pushed back its official dedication ceremony – slated for Aug. 28, the anniversary of the speech – in the face of Hurricane Irene.

“At this moment, when our politics seems so sharply polarized, and faith in our institutions so greatly diminished, we need more than ever to take heed of Dr. King’s teachings,” President Barack Obama said. “I know we will overcome. I know there are better days ahead.”

Obama recognized the dedication and memorial as a “monument to our collective achievement” of overcoming racial segregation and prejudice as a nation, but said “our work, Dr. King’s work, is not yet finished.”

King’s daughter, Bernice King, said her father was “one of the most hated men in America.”

“He was considered an enemy of the government,” she said. “And here we are 40-something years later, and he’s being honored by our nation.”

She said the dedication represented a time of American pride, as well as the crossing of another “milestone” in the country’s history.

Bernice King also thanked both her parents for their sacrifices.

“I hear my father say we must have a radical revolution of values and a reordering of our priorities in this nation. I hear my father say, as we dedicate this monument, we must rapidly begin the shift from a thing-oriented society, to a person-oriented society,” she said. “I am especially proud to stand here as one of the four children my father referred to when he resounded the American dream that one day, we would live in a nation where we would not be judged by the color of our skin but by the content of our character.”

District Mayor Vincent Gray took the stage at the event to discuss what he considers a current injustice – the lack of voting rights for the District’s representative in Congress. Gray marched with a crowd from Freedom Plaza to the memorial Saturday as part of a rally for the cause.

“Day in and day out, D.C. residents live under the yoke of injustice,” Gray said.

Most speakers at the event conveyed political messages, with former CBS anchor Dan Rather calling for an end to the corporatization and politicization of the news, and the Rev. Al Sharpton’s message that “justice is not 1 percent of the population controlling 40 percent of the wealth.”

Maryland resident Keith Bowrs said he was proud to be at the event. Bowrs is a brother of the Alpha Phi Alpha fraternity, the same group King joined.

“As a brother of Alpha Phi Alpha, it means so much to see one of my brothers glorified on the national mall,” Bowrs said. “It means so much for me to be here to witness it.”