WASHINGTON (AP) — The St. Louis suburb of Ferguson, Missouri, was roiled by racial unrest after 18-year-old Michael Brown, who was black, was shot and killed by Darren Wilson, a white police officer, on Aug. 9. The street clashes there mirrored past, larger-scale riots in multiple U.S. cities, most of them triggered by perceived racial injustice, or an incident involving police, in already tense communities.

As calm begins to take hold and Ferguson takes its place alongside past urban riots, here are some details about racial unrest in the United States: