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He delivered his remarks in front of over 250,000 civil rights supporters from the steps of the Lincoln Memorial.
At the beginning of his speech, King made a reference to the Emancipation Proclamation, which declared millions of African American slaves free in 1863.
King called for civil and economic rights and an end to racism Credit: Getty - Contributor MLK Day was first recognized in 1983 Credit: Getty - Contributor He said, "One hundred years later, the Negro still is not free."
Towards the end of his speech, King described his dreams of freedom and equality arising from a land of slavery and hatred, translating into the theme "I have a dream."
"I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character," King said in 1963.
Who assassinated Martin Luther King Jr? James Earl Ray was convicted of assassinating King at the Lorraine Motel in Memphis, Tennessee.
In 1969, Ray was convicted after entering a guilty plea, thus forgoing a jury trial and the possibility of a death sentence.
He was sentenced to 99 years in prison.
He served 29 years of his sentence until he died on April 23, 1998, at the age of 70.
Dr King was assassinated on April 4, 1968 Credit: Getty - Contributor Martin Luther King Jr. Day became a federal holiday in 2000 Credit: Corbis - Getty When did MLK Day become a federal holiday? In 1983, President Ronald Reagan signed the holiday into law, and it was first recognized three years later.
Some states resisted the holiday, attempting to co-opt its meaning by combining it with other holidays.
It was finally observed in all 50 states as a federal holiday in 2000.