Rev. Martin Luther King Jr.'s peace legacy praised after Ariz. shootings

In South Carolina, the day was an opportunity for the NAACP to underscore its opposition to a Confederate flag that flies outside the Statehouse. It was moved from atop the Capitol dome in 2000 after protests by the group.

"Take down that flag," North Carolina NAACP president, the Rev. William Barber, told the audience at a rally in Columbia. He argued the flag's presence disrespects people not only in South Carolina but across the nation.

But the South Carolina commander of Sons of Confederate Veterans disagreed.

"They have the right to view it any way they wish. ... But I'm telling you it is. It is our heritage, and we will honor it," said Mark Simpson of Spartanburg, whose great-great grandfather was a Confederate soldier.

In Maine, Gov. Paul LePage changed plans and attended a King memorial breakfast just days after saying critics could "kiss my butt."

King is the only American who was not a U.S. president to have a federal holiday named in his honor. He has been recognized on the third Monday in January since 1986.