Across the Bay Area and the state, juvenile detention centers are more than half empty, and the rates of juvenile crime have dropped precipitously over the last two decades.

The Chronicle did a big cover story today about the not-well-understood trend of falling juvenile crime rates, which have been steadily dropping since a well noted spike in the late 1990s.

The Center on Juvenile and Criminal Justice (CJCJ) reported the astonishing figure back in 2016 that juvenile crime in San Francisco had dropped 80 percent over the course of the previous 20 years. CJCJ noted that about 6,000 juveniles were referred to the Juvenile Probation Department in SF in 1996, and in 2015 that number was down to 1,200.

And Child Trends reported on the trend at the national level, saying that overall rates of juvenile crime were significantly down among all races between 1997 and 2015.

According to the Chronicle's analysis, this has meant that about 4,700 fewer juveniles have been killed in California over the last two and a half decades as would have been killed if juvenile homicide rates had remained steady.

Experts have yet to arrive at an explanation for this trend, either at the state or national level. "Nobody knows why this occurred," says Mike Males, a senior research fellow with CJCJ, speaking to the Chronicle. "[The downward trend happened] almost regardless of what local, state or national policies were adopted."

Only one clue in the California data possibly points to the economy — the downward trend reversed and spiked up briefly just before the Great Recession, in 2006, only to begin falling again the next year.

SF District Attorney George Gascon tells the Chronicle he believes that policies around juvenile incarceration changed over the past two decades after research showed that even one stint in juvie could lead to recidivism.

"We recognized that actually institutionalizing people, especially young people for low-level offenses, actually has the reverse impact. It doesn’t deter them," Gascon tells the Chron.

The spike in juvenile crime led to a building boom for juvenile detention halls back around 2000, as well a state proposition imposing harsher sentences on current and former gang members even if they committed minor offenses.

Now those juvenile halls have plenty of space in them. Per the Chron: "Nevada County had an average of five juveniles locked up each day last year in a facility built to hold 60. Alameda County had 66 kids in a building designed for 358."

Violent crime at the national level is at a historic low, as this 2018 report by the Congressional Research Service showed, though rates of violent crime appeared to be on the rise in cities of all sizes between 2015 and 2016.

Still, as the CJCJ reported, there are twice as many arrests each year of people over age 50 in San Francisco than of those under 18.

Vanishing Violence [Chronicle]