23 July 1967,
The U.S. Police raid at a bar where African-American activists from Detroit met brought terrible riots. Fed up with years of police abuse and structural racism, black citizens faced the Police and the National Guard for five days. In total, 43 people died in the incidents, 1,400 injured and 7,200 arrested. That summer in the United States there were 159 incidents related to racism.
Source:
Wikipedia - 1967 Detroit riot.