Pennsylvania's prison population grew much faster than any other state's from 2007 to 2008, according to figures released by the Justice Department this week.

While the state and federal inmate count increased less than 1 percent nationwide - the lowest rate in eight years - Pennsylvania's was up 9.1 percent, well ahead of the 4.9 percent of second-place Arizona.

It was no one-year anomaly, said Susan McNaughton, press secretary for the state Department of Corrections.

"We've been experiencing this population growth for quite a while, and we're at a point where we're running low on bed space," she said.

Because of overcrowding, about 500 prisoners have been transferred to county prisons, and the state is seeking accommodations for 2,000 others in at least one other state, she said.

In 20 states, including New Jersey and New York, prison populations fell, in many cases because of efforts by cost-conscious lawmakers.

"It's not ideological. It's pragmatic," said Ram Cnaan, a professor at the University of Pennsylvania's School of Social Policy and Practice. "This is the first time that we have alliances on the right and left on this issue, and it's the money that has forced the issue."

For fiscal 2010, the Pennsylvania Department of Corrections has requested $1.8 billion, an increase of about $200 million, according to the agency's budget presentation.

The department contends that changes are needed to find other ways to treat or punish those who commit lesser crimes, such as drug and property offenses, McNaughton said.

"We believe we really should be saving our expensive prison space for those who are truly violent and who truly need to be separated from society," she said.

Pennsylvania also added more prisoners - 4,178 - than any other state, according to "Prisoners in 2008," by the Bureau of Justice Statistics.

One factor was the two-month moratorium on paroles last fall after a parolee gunned down Philadelphia Police Sgt. Patrick McDonald.

During the moratorium, the state prison system grew by about 1,100 inmates, but that total wasn't needed to make the state first for percentage growth.

In absolute numbers, Pennsylvania ranks behind six states.

On Dec. 31, 2008, California had 173,670 prisoners, edging out Texas' 172,506. Each of those states had more than No. 3 Florida's 102,388 and No. 4 New York's 60,347 combined.

Georgia and Ohio also had more than Pennsylvania's 50,147 - 47,193 of them men, 2,954 women.

New Jersey's state and federal prison population - which declined 3.3 percent, tying Kentucky and trailing only New York's 3.6 percent drop - was 25,953.