After decades of prisoner escalation, an uncertain leveling-off

The U.S. prison population is finally leveling off after decades of sharp increases. But why? To understand, it helps to have some background.

Starting in the late 1970s, the national prison population rose every year for two decades, peaking at 1,615,487 in 2009, according to the Bureau of Justice Statistics. During that time span, the number of people incarcerated in Pennsylvania state prisons rose more than 500 percent, from 7,814 inmates to 51,429. There were seven years during that stretch in which Pennsylvania saw a double-digit increase in its inmate count.

Since then, the national prison population has dropped about 2.8 percent, and Pennsylvania's has remained relatively steady. New Jersey's inmate population peaked in 1999 at 31,493 inmates -- up from 5,869 in 1979 -- and has declined most years since, falling to 23,225 in 2012.

The factors that drove the inmate boom are complicated. Experts cite the war on drugs and tough-on-crime policies of the 1980s and 1990s, such as three-strikes laws and mandatory minimums as key contributors.

Additionally, new prisons were built at a rapid rate, and staffing those correctional facilities provided good jobs in many communities, providing little economic incentive to reduce inmate populations. The surge in incarceration created communities with large numbers of essentially orphaned children and contributed to high levels of poverty and crime in those areas, said Heather Thompson, a history professor at Temple University who studies mass incarceration.

More recently, in Pennsylvania, a parole moratorium in 2008 -- put in place after a recently paroled Daniel Giddings fatally shot Philadelphia Police Sgt. Patrick McDonald during a traffic stop -- halted the release of thousands of inmates, backing up the parole process for years, according Bret Bucklen, the state Department of Corrections director of planning, research and statistics. The moratorium was lifted after a few months, but its effects lingered, he said.

In general, decreasing crime rates and increased efforts to divert select offenders to programs like drug courts, home detention and halfway houses are the main factors driving the current decline, said Marc Mauer, executive director of The Sentencing Project, a group that promotes corrections reforms.

Both Pennsylvania and New Jersey have taken steps to reduce the number of people sent back to prison for technical parole violations, such as missing curfew. Pennsylvania recently streamlined its parole-docketing process to get more inmates with good odds for parole in front of the board.

Cash-strapped governments are also taking a more critical look at the costs associated with building and staffing new prisons. In 2012, Pennsylvania Gov. Tom Corbett signed a prison-reform package that, in addition to the parole changes, expanded alternative sentences and called for savings from the measures to be reinvested into specialty courts, reentry assistance, victims services and other programs aimed at reducing recidivism. And, in New Jersey, Gov. Chris Christie signed a bill in 2012 that expanded the state's drug court system.

Still, the decreases have been slow and small, and the recent stabilization of the prison population may be precarious, experts say.

Criteria for inmates eligible for diversion and early-release programs have been fairly strict, lessening their impact, said Angus Love, executive director of the Pennsylvania Institutional Law Project, a Philadelphia-based nonprofit that provides legal services to the incarcerated.

Judges have also been somewhat reluctant to sentence significant numbers of offenders to those programs.

And bills continue to be introduced that would make some sentences more severe.

Since the 2012 prison reforms, "no less than 23 bills passed out of the House" that have the potential to raise the Pennsylvania's state prison population, Secretary of Corrections John Wetzel told lawmakers at a budget hearing in February. "You go, ' Oh, we're spending so much money on corrections,' and you keep passing the same bills."