Forget tall fences topped with razor wires or heavily armed guards or patrol points high above. Many US prisoners seem so aged that it would seem ludicrous to think of any kind of precautions to keep them behind bars. You may find them slumped in wheelchairs, or leaning on walkers or canes.
Tough sentencing laws passed in the crime-busting 1980s and 1990s seem to have led to a situation wherein geriatric inmates have become a majority and taking care of their health needs is becoming a huge burden on the cash-strapped states.
"It keeps going up and up," said Alan Adams, director of Health Services for the Georgia Department of Corrections. "We've got some old guys who are too sick to get out of bed. And some of them, they're going to die inside. The courts say we have to provide care and we do. But that costs money."
The trend is particularly pronounced in the South, which has some of the nation's toughest sentencing laws. In 16 Southern states, the growth rate has escalated by an average of 145 percent since 1997, according to the Southern Legislative Conference.
Rising prison health care costs particularly for elderly inmates helped fuel a 10 percent jump in state prison spending from fiscal year 2005 to 2006, according to the National Conference of State Legislatures. That growth in spending is projected to continue, the group said.
The graying of the nation's prisons mirrors the population as whole. But many inmates arrive in prison after years of unhealthy living, such as drug use and risky sex. The stress of life behind bars can often make them even sicker.
And once they enter prison walls, they aren't eligible for Medicaid or Medicare, where the costs are shared between the state and federal government, meaning a state shoulders the burden of inmate health care on its own.
Estimates place the annual cost of housing an inmate at $18,000 to $31,000 a year. There is no firm separate number for housing an elderly inmate, but there is widespread agreement that it's significantly higher than for a younger one.
In addition to medical costs there are other, less obvious expenses. For instance, elderly inmates can't climb to the top bunk so they sometimes need to be housed in separate units that require more space.
The U.S. Supreme Court ruled in 1976 that inmates have a constitutional right to health care. But what that means can depend on where an inmate is locked up.
In Alabama, the Southern Center for Human Rights in 2005 filed a federal class action lawsuit to force the Hamilton Aged and Infirm Correctional Facility to improve conditions. Prisoners with serious medical conditions sometimes had to wait several months or more for treatment at the overcrowded facility housing frail inmates with dementia and Alzheimer's, the lawsuit said.
A federal judge in 2006 appointed a receiver to oversee California's prison system after finding that an average of one inmate a week was dying of neglect or malpractice. A new report issued by the receiver found that as many as 66 inmates died last year because of poor medical care.
State lawmakers have been reluctant to tinker with the tough laws that are keeping more people in prison for longer sentences. Reacting to violent crime waves in the 1980s and 1990s, state lawmakers passed two- and three-strikes laws and abolished parole.
They are now seeing the results of those laws, said Ronald Aday, professor of aging studies at Middle Tennessee University who has written a book on aging prisoners.
"This number is going to keep going up and up until they address the issues that are putting these people there in the first place," Aday said.
At Men's State Prison in central Georgia, the older inmates stick together, said Manson Griffin, 66, and Joe Williams, 62.
They rattle off a list of ailments common to men their age: arthritis, high blood pressure, bad backs. Williams wears a neck brace and walks with a cane. Both are taking a laundry list of prescription medications.
Still, Griffin said he's in fairly good condition compared with some of the older inmates at Men's, where the average age is 52 and the oldest prisoner is 86.
"It's heart-rending to see some of the older people in the condition they're in," Griffin said. "You have to wonder why they haven't had a little leniency on them to let them go home?
"What can an 80-year-old man in a wheelchair do? Run?"