The March on Washington for Jobs and Freedom (or "The Great March on Washington", as styled in a sound recording released after the event) was one of the largest political rallies for human rights in United States history, and called for civil and economic rights for African Americans. It took place in Washington, D.C. on Wednesday, August 28, 1963. Martin Luther King, Jr., standing in front of the Lincoln Memorial, delivered his historic "I Have a Dream" speech advocating racial harmony during the march.

The march was organized by a group of civil rights, labor, and religious organizations, under the theme "jobs, and freedom."  The march is widely credited with helping to pass the Civil Rights Act (1964) and the Voting Rights Act (1965). 

From Wikipedia:  http://en.wikipedia.org/wiki/March_on_Washington_for_Jobs_and_Freedom