His efforts in the civil rights movement led to the March on Washington in 1963 where he delivered his famous 'I Have a Dream' speech. With this march, he brought the attention of the entire nation to the civil rights movement.

In 1964, he became the youngest person to receive the Nobel Peace Prize for his efforts to end segregation and racial discrimination through non-violent means.

In a recent poll, most Americans said there was significant progress in achieving King's dream of racial equality.

It is a testament to the greatness of King that nearly every major city in the US now has a street or school named after him.

King always stressed the importance of the ballot. He argued that once all African-Americans had the vote they would become an important political force.

Although they were a minority, once the vote was organised, they could determine the result of presidential and state elections. This was illustrated by the African-American support for John F Kennedy that helped give him a narrow victory in the 1960 election.

And Barack Obama's amazing run in the Democratic primaries only validates King's belief.

Image: King attends a prayer pilgrimage for freedom May 17, 1957, in Washington, DC.
Photograph: National Archive/Newsmakers