Born in 1929, Martin Luther King Jr.‘s actual birthday is January 15 (which in 1929 fell on a Tuesday). The earliest Monday for this holiday is January 15 and the latest is January 21. The Monday observance is similar for those federal holidays which fall under the Uniform Monday Holiday Act.

The campaign for a federal holiday in King’s honor began soon after his assassination in 1968. President Ronald Reagan signed the holiday into law in 1983, and it was first observed three years later on January 20, 1986. At first, some states resisted observing the holiday as such, giving it alternative names or combining it with other holidays. Official observance in each state’s law as well as federal law occurred in 2000.