Washington, Jan 10 (IANS): Martin Luther King Jr.'s birthplace has officially become National Historical Park, in a move to mark his birthday, which is observed on the third Monday of January each year as a US federal holiday.

US President Donald Trump signed the measure aboard Air Force One after arriving in the southeastern state of Georgia on Monday. He flew there to attend the College Football Playoff National Championship Game, Xinhua reported.

"Through his life and work, Dr. Martin Luther King Jr. made America more just and free," White House deputy press secretary Hogan Gidley said.

"This important historical park tells his story, and this bill will help ensure that the park continues to tell Dr. King's story for generations to come," he added.

King's birthplace was already considered a National Historic Site. The bill signed by Trump on Monday upgrades its status to a National Historical Park, and also expands the boundaries to include the Prince Hall Masonic Temple, the headquarters of the civil rights organisation co-founded by King.

King, the major icon of the US civil rights movement, was born on January 15, 1929, in Atlanta, Georgia. He was assassinated in Memphis, Tennessee, in 1968.