The summer of 1967 was a season divided by emotion.

For the bohemians in San Francisco, it was the Summer of Love: an embrace of free love, psychedelics, and rock 'n' roll. But for many black people across the country, the summer of 1967 was something else entirely: a release of pent-up resentment over institutionalized unemployment, abusive policing, and shoddy housing.

Sept. 1, 1967 | Policemen in riot gear enforce a citywide ban on demonstration as the NAACP Youth Council attempts to march to their burned-out "Freedom House" in Milwaukee, Wisconsin. | (AP Photo)

In the first nine months of the year, the federal government recorded 164 "civil disorders" in 34 states. But tensions peaked during the sweltering summer months, fueling a wave of violent protests in more than 150 cities. It would become known as the "long, hot summer of 1967."

The National Guard was deployed in at least a dozen states; news networks broadcast footage of troops descending upon the chaotic streets of Detroit alongside scenes from the Vietnam War.

"No one is safe on the streets, in his home, or on his property," Sen. Everett Dirksen (R-Ill.) said early that summer. "We are rapidly approaching a state of anarchy."

By the time the smoke cleared in September, the tally of destruction was staggering — at least 83 dead, thousands injured, and tens of millions of dollars in property damage, with entire neighborhoods burned to the ground.

July 1967 | Michigan National Guardsmen stand at the ready as firemen battle one of numerous blazes in riot-torn Detroit. | (AP Photo)

At the heart of the unrest was black anger over racial injustice and oppression. The 1964 Civil Rights Act may have banned segregation and employment discrimination, but for blacks across the country — not just in the South — life three years later was still far from civil. In fact, it was often instances of violence against black Americans, particularly by police, that triggered the riots in the first place.

In Newark, New Jersey, reports of a black cab driver being beaten by officers during arrest sparked immediate backlash on July 12, culminating in a commercial district being set aflame and 23 black men, women, and children dead at the hands of the military. In Detroit, a police raid of an after-hours club filled with black patrons on July 23 set off five days of violence, which left 43 people dead, thousands injured, and more than 7,000 arrested.

July 23, 1967 | A man hurls a shoe at police in Detroit. | (AP Photo)

At the end of July, President Lyndon B. Johnson set up a commission to investigate the cause of the riots. The findings — known as the Kerner Report — published in March 1968 argued that "white racism is essentially responsible for the explosive mixture which has been accumulating in our cities since the end of World War II." Pervasive discrimination and segregation in employment, education, and housing created massive and growing concentrations of black ghettos "where segregation and poverty converge on the young to destroy opportunity and enforce failure."

"Our nation is moving toward two societies, one black, one white — separate and unequal," it said.

The analysis won widespread acceptance among both blacks and whites.

July 24, 1967 | A Michigan state officer searches a young man in Detroit. | (AP Photo/file)

"A riot is the language of the unheard. And what is it that America has failed to hear?" Martin Luther King Jr. said in a speech in April 1967. "It has failed to hear that the promises of freedom and justice have not been met. And it has failed to hear that large segments of white society are more concerned about tranquility and the status quo than about justice, equality, and humanity."

The "long, hot summer of 1967," particularly in Detroit, was one of the most violent urban revolts of the 20th century. It was not, however, the first, nor would it be the last — Martin Luther King's assassination less than a year later sparked another wave of violence.

Here are a few more harrowing moments from that burning summer when the dark reality of America's race problem was so brutally exposed.

July 25, 1967 | National Guardsmen escort a fire truck into the riot area of Cambridge, Maryland, as debris from a fire continues to smolder. | (AP Photo/Bob Schutz)

July 23, 1967 | A man is taken into custody in Detroit. | (AP Photo/Alvin Quinn)

June 15, 1967 | A Youth Patrol, created to help restore order to the riot-torn sections of Tampa, meet with a city administrator. | (AP Photo/Toby Massey)

July 26, 1967 | Captured men peer from under a garage door, guarded by an Amy trooper, in Detroit. | (AP Photo)

July 16, 1967 | Picketers calling for the removal of National Guard troops from Newark march near City Hall. | (AP Photo)

July 28, 1967 | With National Guardsman standing watch, women arrested during the rioting in Detroit board a bus for transfer to a nearby detention home. | (AP Photo)

July 15, 1967 | A man is forced to lie on the pavement as New Jersey state police stand guard in Newark. | (AP Photo)

July 25, 1967 | Women and children stroll past the remains of homes caught in the path of the rioters in Detroit. | (AP Photo)

July 1967 | A Detroit shop owner tries to keep his storefront clean. | (AP Photo)

Aug. 1, 1967 | Pallbearers carry the tiny casket of Tanya Blanding, 4, a victim of riots in Detroit. The girl was killed as a hail of police and National Guard bullets swept an apartment building where she huddled on the floor. | (AP Photo)

Aug. 14, 1967 | A white woman stands in protest with a Confederate flag as a group of civil rights marchers pass through Hammond, Louisiana. | (AP Photo/Jack Thornell)