Aging prison populations are straining state budgets as lawmakers struggle to arrive at solutions to the growing problem.

The number of state and federal prisoners over the age of 55 has increased from 43,300 in 1999 to 76,400 in 2008 in the United States. That is an increase of roughly 76%, according to a Washington Post report. Recent cost estimates from the American Civil Liberties Union place the cost of housing older inmates at close to $72,000 per year, compared with just $24,000 for younger inmates. The growth in the number of older prisoners is likely the result of public policies like the “Three Strikes” rule, a mandatory minimum sentencing law, according to the Post.

A number of states are exploring ways to reduce the number of costlier, older prisoners in their care. At least 12 states have adopted or expanded early-release programs in the last year. While some experts note that conventional nursing home care would be cheaper than prison-based care, there is a fear of releasing prisoners, especially violent sex-offenders, into the general public, according to the Post.