Extract the answer to the question from the following context. Question: What sparked the clashes? Context: In June 1963, Rev. Martin Luther King, Jr. gave a major speech in Detroit that foreshadowed his "I Have a Dream" speech in Washington, D.C. two months later. While the African-American Civil Rights Movement gained significant federal civil rights laws in 1964 and 1965, longstanding inequities resulted in confrontations between the police and inner city black youth wanting change. Longstanding tensions in Detroit culminated in the Twelfth Street riot in July 1967. Governor George W. Romney ordered the Michigan National Guard into Detroit, and President Johnson sent in U.S. Army troops. The result was 43 dead, 467 injured, over 7,200 arrests, and more than 2,000 buildings destroyed, mostly in black residential and business areas. Thousands of small businesses closed permanently or relocated to safer neighborhoods. The affected district lay in ruins for decades. It was the most costly riot in the United States.
the African-American Civil Rights Movement