"While others were advocating for freedom by 'any means necessary,' including violence, Martin Luther King Jr. used the power of words and acts of nonviolent resistance, such as protests, grassroots organizing, and civil disobedience to achieve seemingly impossible goals," according to The King Center.

The U.S. is marking Martin Luther King Day, a federal holiday. But in Alabama and Mississippi, it's also Robert E. Lee Day, in honor of the Confederate general.

Federal and state offices, banks, as well as postal and trash services will be closed or suspended Monday. Here’s what else you should know.