Thousands of people are gathering in Washington to remember the Reverend Martin Luther King Jr's landmark "I Have a Dream" civil-rights speech half a century ago.
In 1963, African-Americans were struggling to overcome racial discrimination - practices in various parts of the United States that restricting voting, blocked fair access to good jobs, and left many more mired in poverty.
Fifty years later, speakers intend to note the progress that has been made since then, and the many problems that remain. Those at the podium include another African-American preacher, the Reverend Al Sharpton, as well as King's son, Martin Luther King III.
Wednesday is the actual anniversary of the speech (August 28). It will be marked by another march in Washington and speeches from U.S. President Barack Obama, the country's first African-American president, as well as former presidents Jimmy Carter and Bill Clinton.
The civil-rights movement attracted attention and gained political momentum in the mid-1950s when King, a young black preacher, led the successful drive to desegregate public buses in Montgomery, Alabama.
King organized non-violent protests against southern segregation and supported the struggle for black equality and voting rights that helped bring laws banning discrimination in voting and public accomodations.
King won the Nobel Peace Prize in 1964 and was assassinated in 1968 in Memphis, Tennessee.