Last week, I noted that the United States puts more youths and teenagers in jail than any other developed country, with about 70,000 detained on any given day in 2010. And there's plenty of evidence suggesting that this policy does far more harm than good.

Karen Bell, secondary-school math chair, teaches geometry at the Fairfax County Juvenile Detention Center school. (Jahi Chikwendiu / The Washington Post)

But there's another, important twist to this story: The U.S. incarceration rate for youths has actually dropped 32 percent over the past decade, according to a new report (pdf) from the National Juvenile Justice Network and Texas Public Policy Foundation. And there's good reason to think the numbers can keep falling.

Some of the drop has been driven by the general decline in crime and arrests across the country. But not all. Importantly, another chunk of the drop is due to the fact that nine states — including California, New York and Texas — have been experimenting with new policies to keep kids who commit minor offenses out of jail. These nine states have all seen an even bigger drop in their youth confinement rates since 2000.

"Over the past decade, some states have stopped to take a second look at their youth prisons," says Sarah Bryer of the National Juvenile Justice Network. "Their budgets were hemorrhaging, so they stopped and asked if they were really getting the best bang for their buck. And the research showed that these facilities were enormously expensive — and often weren't actually improving public safety."

So how did they go about shrinking prisons? Take California. Since 2007, the state began to close some of its detention facilities to save money. At the same time, the legislature outlawed confinement for kids who had only committed minor, non-violent offenses. And the state poured some of the savings into alternative programs (which can include drug treatment, home monitoring, or mental-health services).

As a result, California's youth incarceration rate declined 40 percent over the last decade — a steeper fall that in the rest of the country and dropping faster than the state's arrest rate for youths.

The eight other states that took comparable approaches were Connecticut, Mississippi, New York, Wisconsin, Illinois, Ohio, Texas and Washington. The table below, from the report, provides a quick look at some of the strategies they pursued to reverse the sharp run-up in detention rates during the 1990s:

The report notes, however, that there's a lot more work that can be done. For instance, there are reams of evidence that alternatives to incarceration work in some cases — a mental-health program might do more for public safety, say, than throwing a kid in jail. But only 5 percent of youths who might be eligible for these programs actually participate.

What's more, while detention might be unavoidable for violent youths or murderers, that's only a portion of who's actually in jail. In 2010, the report notes, 41,877 youths were confined for minor offenses "such as breaking school rules, running away from home, and missing a parole hearing." Again, researchers have found that throwing these kids in detention makes them less likely to graduate and more likely to commit more serious crimes later on.

Still, Bryer is optimistic that the detention rate will continue to decline — and that more states will adopt the sort of policies that California and Texas are experimenting with. Among other things, she notes that there's a growing bipartisan consensus that the current detention policies don't work very well. (The report, she notes, was co-written with the Texas Public Policy Foundation, a more conservative, free-market think tank.)

"We’re excited about the downward trend," she said. "Kids who make mistakes do need to be held accountable — but in ways that help kids get back on track. Research has found that finding ways to hold them accountable in collaboration with families and communities and schools can work. Removing those supports and sticking kids back in detention is not always helpful."

Further reading:

-- The Annie E. Casey Foundation has done an enormous amount of research on ways to reduce juvenile detention rates. Here's a 2009 report laying out some policies to cut pre-trial detention, and here's a 2013 update finding that many of them have been quite successful. Here's another report making a more in-depth case for reducing overall incarceration rates.

-- Here's a look at some research on the negative effects of throwing youths in prison.