Tuesday marks one of the rare instances where President Obama will tackle the issue of race relations in the United States. (Jacquelyn Martin/AP) Wednesday marks one of the rare instances when President Obama has tackled the issue of race relations in the United States. (Jacquelyn Martin/AP)

When President Obama addresses the "Let Freedom Ring" rally Tuesday afternoon to commemorate the 50th anniversary of the March on Washington, it will mark one of the rare instances when he has addressed the question of race before a national audience. Here are a few highlights of how he has tackled the issue of both U.S. race relations and the Rev. Martin Luther King Jr.'s legacy in the past.

1. His 2008 campaign speech on the Rev. Jeremiah Wright. During Obama's first presidential bid it came to light that his Chicago pastor, Jeremiah Wright, had made a series of controversial remarks in the wake of the Sept. 11, 2001, attacks, suggesting that "America's chickens are coming home to roost." In response, then-senator Obama delivered an address in Philadelphia titled "A More Perfect Union," in which he described the unusual place he occupies when it comes to race.

"I am the son of a black man from Kenya and a white woman from Kansas. I was raised with the help of a white grandfather who survived a Depression to serve in Patton's Army during World War II and a white grandmother who worked on a bomber assembly line at Fort Leavenworth while he was overseas. I've gone to some of the best schools in America and lived in one of the world's poorest nations," Obama said. "I am married to a black American who carries within her the blood of slaves and slaveowners - an inheritance we pass on to our two precious daughters. I have brothers, sisters, nieces, nephews, uncles and cousins, of every race and every hue, scattered across three continents, and for as long as I live, I will never forget that in no other country on Earth is my story even possible."

And while Obama criticized Wright's comments for expressing "a profoundly distorted view of this country," he said he could not disown his former pastor. "I can no more disown him than I can disown the black community. I can no more disown him than I can my white grandmother - a woman who helped raise me, a woman who sacrificed again and again for me, a woman who loves me as much as she loves anything in this world, but a woman who once confessed her fear of black men who passed by her on the street, and who on more than one occasion has uttered racial or ethnic stereotypes that made me cringe," he said. "These people are a part of me. And they are a part of America, this country that I love."

2. His remarks on the arrest of prominent Harvard University professor Henry Louis "Skip" Gates, Jr., outside his Cambridge, Mass., home. Upon returning from a business trip in July, 2009, Gates tried to force open the jammed door of his home with the help of his driver; Cambridge police arrested him after a neighbor in the largely-white neighborhood reported seeing two black men breaking into the house.

In a press conference in the East Room, Obama said that he did not know "what role race played" in the incident, "But I think it's fair to say, number one, any of us would be pretty angry; number two, that the Cambridge police acted stupidly in arresting somebody when there was already proof that they were in their own home; and, number three, what I think we know separate and apart from this incident is that there's a long history in this country of African Americans and Latinos being stopped by law enforcement disproportionately," Obama said. "That's just a fact."

Obama added that African Americans and Latinos had made "incredible progress" over the years when it comes to discrimination, "And yet the fact of the matter is it still haunts us."

Less than two days later president sought to "recalibrate" his remarks and hosted a meeting between himself, Vice President Biden, Gates and the officer who had arrested Gates, Sgt. James Crowley, at the White House. The four men shared beers, prompting it to be called the "White House beer summit."

3. His 2013 comments on the acquittal of George Zimmerman in the killing of Florida teenager Trayvon Martin. On July 19 -- nearly a week after a jury acquitted Zimmerman of intentionally murdering Martin -- the president delivered an extensive and deeply-personal set of remarks in the White House briefing room about why the black community was so angry and hurt in the wake of the verdict.

Trayvon Martin could have been me 35 years ago,” Obama said, during a talk that lasted for 18 minutes. “And when you think about why, in the African American community at least, there’s a lot of pain around what happened here, I think it’s important to recognize that the African American community is looking at this issue through a set of experiences and a history that — that doesn’t go away.”

Obama also had addressed Martin's killing during a March 2012 event in the Rose Garden, when he remarked, "“If I had a son, he’d look like Trayvon. When I think about this boy, I think about my own kids.”

But his July 2013 remarks were more pointed, as he explained to non-black Americans the toll racial profiling takes over the course of a lifetime. "There are very few African American men in this country who haven’t had the experience of being followed when they were shopping in a department store. That includes me.”