It has to be one of the most famous and iconic speeches of modern times and represents one of the key moments of the Civil Rights movement during the 1950s and 60s.
One theory on why the speech has had such a lasting impact is that it made a difference, it helped change things. It contributed to the passing of the 1964 Civil Rights Act and the 1965 Voting Rights Act.
Nobody remembers great speeches that make no difference or have no lasting effect.
Like many people, I've been wondering this week how close America has come in the last 50 years to realising Dr King's dream.
Is America are more racially tolerant and equal society? Are people judged in Dr King's words by the content of their character rather than the colour of their skin?
Clearly America has come a long way since 1963. Could there be any more obvious example then Barack Obama, the first black President?
Along with the President, African Americans occupy positions of power and influence in areas like politics, business, media, entertainment and sport that were unimaginable 50 years ago.
As a black person growing up and living in the UK, America has always been an inspiration in terms of what black people can achieve in so many different areas of society.
The problem I see is that although America may offer more opportunities individually for African Americans, it's hard to argue that collectively African Americans are in a better position now than 50 years ago.
When it comes to jobs, housing, education, health, and the criminal justice system, African Americans experience greater levels of inequality and disadvantage than white Americans.
I can't help but think that America is still an institutionally racist country; where being black means your life chances and opportunities are not equal to whites.
This is why Dr King's dream hasn't been realised and will continue to act as a reminder that the Civil Rights struggle is ongoing and has much to achieve.