Twenty years ago this week, a jury acquitted the Los Angeles policemen who beat motorist Rodney King, and the city exploded in a six-day riot. Before it was over, there were more than 50 deaths, about 2,500 injuries, and half a billion dollars or more in property damage. The riot led to alarming predictions that a new age of urban unrest might be at hand. What happened in the next two decades, though, was very nearly the opposite: Cities in the United States have been relatively riot-free over the last two decades.
But that peace should not make us feel too smug. The lack of rioting in urban America lately is primarily because of the competence of law enforcement agencies — including, notably, the Boston Police Department — not because we have solved the problems of race and poverty that can fuel rioting.
America has a long history of urban disorder, like New York’s 1863 Draft Riot, where hundreds died. The 20th century was an epoch of race riots, beginning in New Orleans in 1900 and ending in St. Petersburg, Fla., in 1996. Whites were the aggressors in the early race riots, like the ones in Atlanta in 1906 and Chicago in 1919. Tales of alleged misdeeds stoked racist fires and already discriminated-against African-Americans became victims of white violence. From the 1960s to the 1990s, African-Americans led the rioting, in response to perceptions of injustice, like the acquittal of the policemen in Los Angeles in 1992.
Riots are an urban phenomenon because there must be enough people to overwhelm the local police force. The disorder typically ends when the authorities bring in enough overwhelming force, as when the Union Army came to New York in 1863. In the 1960s, the United States was one of the two world leaders in rioting, along with India. So why, since 1992, have we become a far less tumultuous place?
My research on rioting, written with Denise DiPasquale, points to two factors that help explain when and why violence breaks out: underlying social conditions and police strength.
Social factors usually get more attention. In the 1960s, cities with a higher nonwhite unemployment rate were more likely to have riots and had more arson when riots did occur. In 1990, in South Central Los Angeles, 1 in 4 young African-Americans were unemployed.
Some problems, to be sure, are slowly getting better: We have now undone the rise in segregation that occurred between 1910 and 1960. Yet social improvement only goes so far in explaining urban America’s recent tranquility. While racial segregation has significantly declined, poorer African-American communities remain stubbornly separated. Unemployment, the most reliable statistical correlate of rioting, is strikingly high; the rate for African-American men is 14 percent, as opposed to 7 percent for white men. Young men with too much time on their hands can be prone to violence.
Meanwhile, the evidence suggests that police conduct is at least as important in preventing rioting. In the 1960s, cities that spent more on cops had riots with fewer arsons and arrests. Riots were dramatically rarer in Southern cities, despite the greater pervasiveness of racial discrimination, perhaps because Southern cities were more likely to respond brutally to any urban disorder.
Dictatorships, of course, can maintain order at the point of a gun. But there are other ways for police to defuse tensions that lead to rioting. Better policing methods involve an abundance of smart strength, simultaneously demonstrating that rioting will fail and that the concerns of the uprising are being heard. We experience the strength of the Boston Police Department every day in the relative safety of our streets. The department’s strategy of community connection helps in everyday interactions, but it also created skills that proved so helpful in handling the Occupy Boston movement.
Traditional confrontational methods could have easily turned Occupy Boston into a bloody urban explosion, but Boston police built relationships with the movement instead. Those relationships helped ensure the relatively calm clearing of the Greenway last December.
In the end, though, it’s disconcerting when peace is being preserved by police brawn or police brain — rather than by a shared sense of opportunity. So we should celebrate the success of Boston police, but only up to a point. The underlying problems that are often associated with rioting remain with us. The best tool against racial injustice — and the riots injustice can foment — is better education and the economic success it can engender.Edward L. Glaeser, a professor of economics at Harvard University, is author of “The Triumph of the City.’’ His column appears regularly in the Globe.