NEW YORK (AP) — Spurred by budget crises, California and Michigan together reduced their prison populations by more than 7,500 last year, contributing to what a new report says is the first nationwide decline in the number of state inmates since 1972.

The overall drop was slight, according to the Pew Center on the States — just 0.4 percent — but its report suggests there could be a sustained downward trend because of keen interest by state policymakers in curtailing corrections costs.

“The political and policy environment has changed drastically,” said Adam Gelb, director of the Pew Center’s Public Safety Performance Project.

“There’s now a realization on both sides of the aisle that there are research-based strategies to protect public safety and hold offenders accountable without sinking ever more public dollars into prisons,” Gelb said.

According to official state data collected by the Pew Center, 1,403,091 people were under the jurisdiction of state prison authorities on Jan. 1, down by 5,739 from a year earlier. The report, being released Wednesday, said this was the first year-to-year drop in the state prison population since 1972, when there were about 174,000 prisoners.

Since then, the nationwide prison population has soared, in part because of stiff sentencing laws, giving the U.S. the world’s highest incarceration rate.

With more inmates to handle, state corrections costs quadrupled over the past 20 years, according to the report. Many states are now in fiscal disarray, and legislators are looking afresh at ways to curb prison spending, but the Pew survey revealed a wide variation of responses.

In 23 states, the number of prisoners increased in 2009 — notably in Indiana by 5.3 percent and in Pennsylvania by 4.3 percent.

However, 27 states reduced their prison populations — led by California with a drop of 4,257 and Michigan with a drop of 3,260. New York, Maryland, Texas and Mississippi also reduced their prison populations by more than 1,000.

A look at developments in some key states:

— California: A new law, created to ease prison overcrowding and help close the budget deficit, enables inmates to reduce their sentences by up to half through good-behavior credits. The state also has sought to cut the number of low-risk parolees returning to prison for technical violations of parole terms.

— Michigan: Since reaching an all-time high of 51,554 in March 2007, Michigan’s prison population has been cut by more than 6,000, according to the Pew report. The state has reduced the number of inmates who serve more than their minimum sentence, decreased parole revocation rates and enhanced supervision of re-entry programs for newly released offenders.

— Rhode Island: In percentage terms, Rhode Island had the biggest drop in prison population last year — 9.2 percent — in large part because of a new law that enables some prisoners to get out early if they commit to rehabilitation programs such as job training and substance abuse treatment.

Although California, Michigan and Rhode Island have fiscal problems that are among the nation’s worst, Gelb said the move toward reduced prison populations was not driven solely by the economic downturn. He noted that Texas decided in 2007, before the recession, to strengthen probation and re-entry programs rather than commit to construction of several new prisons.

Michael Thompson, director of the Council of State Governments’ Justice Center, urged states to avoid rash, deficit-driven decisions and reinvest funds saved on prisons in other programs that would reduce recidivism.

“You want to make sure policymakers are not just trying to balance their budgets and jeopardize public safety in the process,” he said. “You can actually find interesting ways to reduce corrections spending and increase public safety — but not every state is doing that.”

Among the 23 states where the prison population increased last year, Indiana led in proportional terms, growing by 5.3 percent, while Pennsylvania added the most prisoners, 2,122.

An Indiana prison spokesman, Doug Garrison, said the legislature had enhanced criminal penalties to add prison time to a number of offenses, and the state has not had to release prisoners out of budget constraints or court orders.

Florida added 1,527 more state prisoners in 2009, the second highest increase — at a time when the state is cutting funding for many non-corrections programs.

“The university’s funds were cut,” said Florida State University criminologist Dam Mears. “In the face of that, look at our prison system. They keep the funding going.”

Despite the slight decrease in state prisoners, the Pew report said the nation’s total prison population increased in 2009 because the number of inmates in federal prisons rose by 6,838 to an all-time high of 208,118.

The report did not tally prisoners held in municipal and county jails.

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