It will be historic in part because it is the 45th anniversary of Martin Luther King Jr.'s historic "I Have a Dream" speech. He will be the first black man to be the nominee of a major political party.
I was in Washington that day in the summer of 1963. I was then working for the Federal Reserve Board as an economist. The crowds were enormous - Washington was a smaller place then.
"This is a monumental moment in our nation's history," Martin Luther King III, the civil rights icon's oldest son, told The Associated Press on Wednesday. "And it becomes obviously an even greater moment in November if he's elected."
Obama was just 2 years old when King addressed a sea of people on the National Mall in Washington on Aug. 28, 1963.
Obama, known for his stirring oratory, has been trying to lower expectations for his acceptance speech.
At the convention's final night, singers Sheryl Crow, Stevie Wonder and will.i.am are scheduled to perform, with Academy Award-winner Jennifer Hudson singing the national anthem.
Former Vice President Al Gore will add his voice to the lineup of Democratic luminaries trying to motivate party members for the fall.
Flashback - King gives I have a dream speech
More than 200,000 people took part in a civil rights rally today at the Lincoln Memorial in Washington, D.C. The rally marked a significant moment in the American Civil Rights Movement. From the steps of the Lincoln Memorial, Martin Luther King, Jr. gave his famous "I have a dream" speech.
Rev. King, head of the Southern Christian Leadership Conference, said: "I still have a dream, a dream deeply rooted in the American dream - one day this nation will rise up and live up to its creed, 'We hold these truths to be self-evident, that all men are created equal,'" said King.
"King's Plea - 'Let Freedom Ring'" Oakland Tribune, August 29, 1963