Today is the 47th anniversary of Dr. Martin Luther King Jr.'s "I Have a Dream" speech. On August 28, 1963, tens of thousands marched for civil rights in an orderly rally in Washington D.C. As people from all over the country marched for jobs and freedom, President John F. Kennedy waited in the White House to see how things would pan out. The crowd grew to about 250,000 and the powerful singing voices of Mahalia Jackson and Joan Baez filled the Lincoln Memorial. Some scholars sum this moment up as, "the most important single day in civil rights history," reports New York Times. Watch the video of Dr. King's powerful "I Have a Dream" speech.