More than 200,000 people listened as the Rev. Martin Luther King Jr. delivered his "I Have a Dream" speech in front of the Lincoln Memorial in Washington, D.C. in 1963. https://abcn.ws/38lYv6Z #MLKDay | ABC News

647K views · 10K reactions | Pres. Trump and Vice Pres. Pence made an unscheduled visit to the Martin Luther King Jr. memorial on Monday afternoon. https://abcn.ws/38njqGE | ABC News | Facebook

WATCH: Dr. Martin Luther King Jr. was assassinated 50 years ago tonight. Chet Huntley reported the news in an NBC News Special Report, seen here. King was in Memphis, Tenn., where sanitation workers, almost all of them black, had been on strike for weeks. The night before he was killed, King gave the last speech of his life, the famous “I’ve Been to the Mountaintop” speech, before an audience of striking workers and their supporters. He ended the speech by saying, "I don't know what will happen