Murder mystery

I started studying the causes and consequences of incarceration for the Open Philanthropy Project. The subject is full of mysteries. Here’s one.

As best we can measure, the US crime rate rose from the mid-1960s to the early 1990s and then reversed:

US crime rate 1960-2012

(Following FBI definitions, this graph is of “Part I” crimes and excludes excludes drug crime, white collar crime, drunk driving offenses, traffic violations, and other minor crimes. The property crime rate is graphed against the right axis, the violent crime rate against the left.)

The strange thing is, the experts aren’t completely sure why the rise and fall. Many theories have been offered, and many may hold truth. There were disproportionately many young men in the late 1960s. Abortion was legalized in the early 1970s. Lead came out of the gas in the late 1970s.

Yet, argues Michael Tonry, the crime drop of the last few decades is not a distinctively American achievement. Crime has fallen in other wealthy, English-speaking countries, and in much of Western Europe.

As a result, according to Tonry, “No one has a really good explanation for why crime rates are falling.” Dills, Miron, and Summers agree. (Farrell, Tilly, and Tseloni also question most theories while arguing that security improvement drove down property crime.)

Probably the rise that started in the 1960s is partly a statistical mirage. Over time, people may have become more apt to report crime to the police, the police more apt to file a report, and local law enforcement agencies more apt to deliver the data to the FBI’s computers.

Also, cultural norms shifted. Tonry again:

[People in the 1960s] would have been much less likely than now to have thought of a blow from a husband, wife, or partner as an assault. Many victims of domestic violence or of bar fights would not have considered themselves to be crime victims and said “no” if asked if they had been assaulted. Many more such people in the 1980s and even more in the 2000s would have answered “yes.”

As Tracy Chapman sang,

The police
Always come late
If they come at all

And when they arrive
They say they can’t interfere
With domestic affairs
Between a man and his wife

The good news is that if the police now “interfere” more than in the past, ultimately sending more domestic abuse reports into the FBI database, that long-term boost to crime reporting probably masks the full drop in actual crime since the early 1990s. Indeed, victimization surveys—which bypass police reports in favor of self-reports from thousands of randomly polled citizens—show an even bigger fall, closer to 75% than the roughly 50% shown above:

US crime victimization rate 1993-2013

(Here, the population denominator excludes children under 12.)

But the crime rise from the sixties to the nineties is not pure mirage. One way to see that is to focus on the murder rate, which is less prone to shifting biases. Fifty years ago, as now, most murders were recognized and reported as such. (The main bias probably trends the other way: as my colleague Howie Lempel pointed out, improving emergency response and emergency medicine may be turning more murders into attempted murders.) In addition, murders are tracked by both health and law enforcement statisticians, which allows cross-checking—and the match is good. Here is the homicide death rate by month from the Centers for Disease Control:

US homicide death rate, monthly, 1959-2013

The US murder rate started to rise around 1965 (despite any gains in emergency response). Most of the murders were committed with firearms.

That rise was also international. Switching to law enforcement agency statistics, here are the US and Canada murder rates by year. (Notice the different scales : the US scale is on the left and Canada’s on the right.)

US-Canada murder rate, annual

The tight US-Canada fit is powerful because it tends to rule out many factors as major drivers of US crime trends. For example, the US prison population has mushroomed since the early 1980s, while the Canadian one has not. So it’s hard to see then how all that American punishment should get much credit for the crime drop.

Why did the murder rate start to rise around 1965? Clearly, America was at a historical turning point, changing in complex ways. Francis Fukuyama calls it the Great Disruption. Anger bubbled over. Trust in institutions fell. The population under 30, prone to crime, expanded as baby boomers came of age. Did the Great Disruption also somehow cause a crime wave? Fukuyama suggests so, but his argument didn’t convince me, at least in the short form I read.

Freakonomist Steven Levitt has argued that the youth bulge could explain only a fifth of the crime increase then. And if the youth bulge were the driver, why did crime fall even as a second wave—the boomers’ children—swept to adulthood in 1990s?

On November 22, 1966, just about when those murder rate curves bend upward, teenagers in Hollywood demonstrated on Sunset Strip. The spark was a strict new curfew aimed at them. But the demonstration meant more. “Protesters over the 10 o’clock curfew, Vietnam, the racial issue,” said one a news announcer, “fanned the flames of the already excited listeners.” As day turned to night, protest turned to riot. The LA police moved in with billy clubs and tear gas.

Soon after, a musician named Stephen Stills penned a song that accidentally came to be called “For What It’s Worth.” You may not recognize the name, but you know the song:

There’s something happening here
What it is ain’t exactly clear
There’s a man with a gun over there
Telling me I got to beware

Those strains of paranoia and mystery pretty well captured the cultural moment—and criminologists’ confusion about it 49 years later. There’s something happening here. What it is ain’t exactly clear.