The keynote speaker was the Rev. Samuel Rodriguez, president of the National Hispanic Christian Leadership Conference, a socially conservative evangelical association. It marked the first time a Latino had been invited to deliver the King Day address at Ebenezer Baptist.
He urged the audience to complete King's dream.
"Silence is not an option when 30 million of our brothers and sisters live in poverty," he said. "Silence is not an option when 11 million undocumented individuals continue to live in the shadows."
Around the country, parades, service projects and memorials marked the holiday.
Visitors from as far as Europe thronged the National Civil Rights Museum in Memphis, Tenn., the city where King was assassinated in 1968. In Detroit, students beautified schools. Others painted murals honoring King in Arkansas, and Texas residents held rallies and donated items to a food bank.
More than 500 people rallied outside the Alabama Capitol in Montgomery, where state employee Jessie Harris declared Obama's president was a sign of "living the dream" King spoke about.
"We have come far, but the struggle is not over," Harris said.
Associated Press writers Jeffrey Collins in Columbia, S.C.; Jessica Gresko in Washington; and Adrian Sainz in Memphis, Tenn., contributed to this report.
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