US honours King with parades, marches and projects
King was born January 15, 1929, and the federal holiday is the third Monday in January.
In Atlanta, a service was planned at Ebenezer Baptist Church, where King was pastor.
In Memphis, Tennessee, where King was assassinated, an audio recording of an interview with King would be played at the National Civil Rights Museum.
The recording sheds new light on a phone call President John F Kennedy made to King's wife more than 50 years ago.
Historians generally agree Kennedy's phone call to Coretta Scott King expressing concern over her husband's arrest in October 1960 and Robert Kennedy's work behind the scenes to get King released, helped JFK win the White House.