HARRISBURG - Although the number of state prisoners nationwide is on the decline for the first time in almost 40 years, Pennsylvania's prison population continues to spike - with no relief in sight.

Pennsylvania had a 4.3 percent increase in prisoners last year, according to a study released last week by the Pew Center on the States. New Jersey's prison population, in contrast, fell 2.3 percent.

As of Jan. 1, state prisons nationwide held roughly 1.4 million inmates, 0.4 percent fewer than there were on Dec. 31, 2008. That was the first year-to-year drop since 1972, the Pew study found.

Among the main reasons for the decline: States are adopting guidelines reflecting research that shows low-level offenders, as well those who have violated technical aspects of their parole, can be rehabilitated more effectively in community programs rather than in prison.

"We are starting to see a triumph of science over sound bites," said Adam Gelb, director of the Public Safety Performance project at the Pew center.

"State leaders are reaching across the aisle and coming up with research-based corrections strategies for nonviolent offenders that can protect public safety at far less cost than a prison cell," he said.

Pennsylvania has been slow to revamp its sentencing and parole rules, even as the inmate population has been on the rise for decades: It increased 523 percent between 1980 and 2009, from 8,243 to 51,326, according to state Department of Corrections figures.

That increase was compounded in 2008 when Gov. Rendell issued a moratorium on paroles after a paroled felon killed a Philadelphia police officer.

The state now has an overcrowding problem: Prisons have roughly 7,700 more inmates than they can handle.

The problem is so severe that last month, Pennsylvania began shipping inmates to prisons in Virginia and Michigan. The state plans to place 2,000 prisoners out of state by the end of next month.

Corrections Secretary Jeffrey A. Beard has told lawmakers that if the prison population keeps growing, the four prisons under construction will be at capacity when they open.

Such growth comes at a cost: The Corrections Department has requested $1.9 billion in state funding for fiscal 2011. That is an 8.5 percent increase over its $1.75 billion budget this fiscal year.

In his budget address last month, Rendell said the state must reverse the trend of pumping ever more money into housing prisoners. He said increased funding for public education was "one great way to address this problem, because it provides an opportunity for our young people to choose the right path."

"But we need to do more," he said, adding that he would work with the legislature to find other solutions.

In recent years, many states facing overcrowding have shed the tough-on-crime approach of locking up people for longer periods. That approach, they believe, is costly and does not improve public safety.

In Pennsylvania, the legislature has approved initiatives along those lines, including one that reduces minimum sentences for eligible nonviolent offenders.

But other legislatures have been more aggressive, as have some Pennsylvania counties.

In Philadelphia, for instance, the county prison population decreased from a high of 9,854 in January 2009 to 8,369 on Thursday, according to Everett Gillison, deputy mayor for public safety. That, in part, allowed him to cut $9 million from his expected $249 million budget.

The drop is at least partly attributable to a deal last year in which the commonwealth agreed to take 250 state prisoners held in Philadelphia jails.

Another reason, in addition to the falling crime rate, is a program that consolidates hearings for defendants who have probation and parole violations.

Also, judges who have moved from criminal to civil court no longer retain old cases. In the past, some new civil court judges held criminal court once a month to clear their old cases. If there was a problem, hearings were delayed, leaving probation violators in jail for 30, 60, even 90 days before they had a hearing, which often resulted in their release.

State Sen. Stewart Greenleaf (R., Montgomery), who is pushing a number of bills to change sentencing and parole rules, said Pennsylvania's overcrowding had become acute enough to spur legislative action.

"We can't keep operating the way we have," he said. "I think you have to look at law enforcement and the criminal justice system in a new way."

Contact staff writer Angela Couloumbis at 717-787-5934 or acouloumbis@phillynews.com.

Inquirer staff writer Jeff Shields contributed to this article.