During the summer of 1967, 158 riots erupted in urban communities across America. Most shared the same triggering event: a dispute between Black citizens and white police officers that escalated to violence. During those convulsive months, the massive social unrest—alternately labeled riots, rebellions, uprisings and civil disorder—resulted in 83 deaths and 17,000 arrests, according to a 2007 study in The Journal of Economic History. In Detroit, the bloodiest of the uprisings, there were 43 deaths, 7,200 arrests and more than 2,500 buildings looted, damaged or destroyed in five days of rioting. The property damage—adjusted for 2020 dollars—made the ’67 upheavals in Detroit ($322 million) and Newark ($115 million) two of the 10 costliest civil disorders in American history, in terms of insurance claims.

In the riots’ aftermath, President Lyndon Johnson set up the Kerner Commission, an 11-person task force, to investigate why they happened. “Race prejudice has shaped our history decisively; it now threatens to affect our future,” stated the published report in 1968. “White racism is essentially responsible for the explosive mixture which has been accumulating in our cities since the end of World War II.”

Social unrest in Black communities had long been building. A century after emancipation, Black citizens were still barred from many rights and privileges afforded to white Americans. And while the civil rights movement of the 1950s and '60s was making slow inroads, racial injustice and police brutality persisted, fomenting tension. In 1964, two weeks after the landmark Civil Rights Act passed, outlawing racial discrimination, police in New York City shot and killed a Black teen, sparking a six-day-long protest-turned-uprising in Harlem and other large African American communities around the city. In 1965, a traffic stop in the Watts neighborhood of Los Angeles quickly exploded into six days of violence, with more than 30 people dead, more than 1,000 injured and more than 600 buildings damaged or destroyed.

Three months prior to the start of the unrest in Newark and Detroit, Dr. Martin Luther King, Jr. warned of coming violence, even as he pressed for nonviolent direct action: “All of our cities are potentially powder kegs,” said the 1964 Nobel Peace Prize winner in a speech at Stanford University entitled “The Other America.” But, he was careful to note, “I think America must see that riots do not develop out of thin air,” citing persistent poverty and the dismal conditions of segregated housing and schools. “All of these things have brought about a great deal of despair and a great deal of desperation, a great deal of disappointment and even bitterness in the Negro communities.”

Writer and activist James Baldwin, one of the most eloquent critics of racism during the civil rights movement, famously summarized the strife this way to a radio host: “To be a Negro in this country and to be relatively conscious is to be in a rage, almost all the time.” His 1966 essay titled “A Report from Occupied Territory,” published in The Nation, elaborated on the harsh conditions in America’s Black communities, calling out impoverished schools, limited employment opportunities and, especially, racist policing: “The police," he wrote, "treat the Negro like a dog.”

Such treatment had deep roots in American history—from 19th-century slave patrols to Jim Crow-era “Black Codes” (designed to ease the arrest of Black people and profit from their free labor) to police-involved lynchings. By the mid-1960s, “conflicts between Blacks and the police became flashpoints of racial resentment,” as white residents in cities like Detroit and Newark felt threatened by the “Black invasion” to their neighborhoods, writes New York University historian Thomas Sugrue, author of The Origins of the Urban Crisis. “Decades of racial conflict and economic inequality provided the tinder for the 1967 [Detroit] riot; a police action provided the spark.”

In May 1967, the Michigan Civil Rights Commission advised the mayors of cities with large Black populations that the summer ahead had the “potential for racial conflict.” Noting that many incidents of civil disorder had escalated from an incident between a Black citizen and a police officer, the commission called for police departments to “reemphasize the equal application of its rules and regulations regarding courtesy, conduct and language.”

Over the summer of ’67, violent unrest erupted in scores of U.S. cities, including Milwaukee, Buffalo, Tampa and Cincinnati. But the nation was galvanized by the events that transpired in July in Newark and Detroit.

The Newark uprising began on July 12 when a Black cab driver was beaten by two white police officers for a minor traffic offense. The five days of rioting and looting that followed produced 26 deaths, 700 injuries and more than 1,400 arrests. The National Guard and state troopers were called in to restore order. “To some, the flames and violence were riots, wrecking neighborhoods and driving away white and middle-class residents,” wrote Rick Rojas and Khorri Atkinson in The New York Times on the 50th anniversary of the Newark upheaval. “Or was it a rebellion, the uprising of a long-oppressed community that had finally had enough?”

Less than a week after the violence ended in Newark, it began in Detroit—on the night of July 23, when white police officers raided an illegal Black nightclub. In the five days of violence and confrontations that followed, the mostly white police force and military units who deployed to the city were responsible for killing 30 of the 37 Black people who died. As scores of the city’s blocks burned, President Johnson delivered a televised speech to the nation. “Not even the sternest police action nor the most effective federal troops can ever create lasting peace in our cities,” he said. “The only genuine long-range solution for what has happened, lies in an attack, mounted at every level, upon the conditions that breed despair and violence.”

In the first draft of the Kerner Report, entitled “The Harvest of American Racism,” social scientists cited police brutality as the central cause of the uprisings and black discontent in urban America. But the commission buried those findings by the researchers, and President Johnson chose to focus his response on segregation and economic equality. The Kerner Report did acknowledge that the “nation is moving toward two societies, one black, one white—separate and unequal.”

According to Nicole Lewis, a reporter for The Marshall Project, a nonprofit news organization that covers the U.S. criminal justice system, Johnson used the riots to double down on a law-and-order agenda. “In the wake of the violence, two separate and opposing forces formed,” Lewis wrote. “While the Black community pushed for police reform alongside socioeconomic improvement, the federal government responded by equipping police with new tools to control violent expressions of civil unrest.”

Congress passed the Omnibus Crime Control and Safe Streets Act of 1968, a crime bill that authorized $400 million in grants to states to provide resources to local law enforcement.

The ’67 uprisings helped to usher in a new era of Black activism and empowerment that contributed to reforms in law enforcement, economic inequality and the election of the first Black mayors in the early ’70s in both Newark and Detroit.

“The Black community was definitely empowered,” Junius Williams, a Newark-based law professor and civil rights activist, told The New York Times. “Nobody wanted that violence. But at the same time…we had the opportunity to turn that destructive power into something that was positive for the community.”