Martin Luther King Jr., a reverend and civil-rights activist, was assassinated at 39. However, he inspired several movements and political changes.

Today's challenges — from educational inequality and economic disparity, to voter suppression and police violence — demand that we engage with King's full legacy, not just the portions that we’re comfortable with,

The holiday falls on the third Monday of January. A bill to make Martin Luther King Jr. Day a federal holiday was introduced on April 8, 1968 — four days after King was assassinated, according to the National Museum of African American History and Culture.