Martin Luther King Day (officially known as “Birthday of Martin Luther King, Jr.”, and unofficially as ‘MLK Day’), is observed on the third Monday of January in recognition of King’s birthday on January 15th, and is the last federal holiday created in the U.S. The holiday was signed into law by President Ronald Reagan in 1983, and was first observed in 1986 and by all states in some form in 1991. It was not until 2000 that the holiday was named after King by all states. Alabama and Mississippi are the last remaining states to do a joint commemoration of MLK Day and Robert E. Lee’s birthday.