The historical event commemorated annually on Martin Luther King Jr. Day is the legacy and achievements of Dr. Martin Luther King Jr. himself, particularly his leadership during the American civil rights movement. The day, celebrated on the third Monday of January, honors his commitment to nonviolent protest and his vision for racial equality and social justice. King is best known for his pivotal role in the 1963 March on Washington, where he delivered his famous "I Have a Dream" speech. The day serves as a reminder of the ongoing struggle for civil rights and the continuing work needed to achieve equality.