The number of federal prison inmates has grown 27 percent in the last decade, according the Government Accountability Office (GAO).

In a report examining the Federal Bureau of Prisons (BOP) budget, the GAO found that prison population is rising:

The Department of Justice’s (DOJ) Federal Bureau of Prisons (BOP) is responsible for the custody and care of over 219,000 federal inmates—a population that has grown by 27 percent over the past decade. BOP is composed of 119 institutions, 6 regional offices, 2 staff training centers, 22 residential reentry management offices (previously called community corrections offices), and a central office in Washington, D.C. With a fiscal year 2013 operating budget of about $6.5 billion—the second-largest budget within DOJ—BOP projects that its costs will increase as the federal prison population grows through 2018. […] A variety of factors contribute to the size of BOP’s population. These include national crime levels, law enforcement policies, and federal sentencing laws, all of which are beyond BOP’s control.

A growing prison population has increased Justice Department spending on the federal prison system from just over $5 billion in fiscal year 2008 to nearly $7 billion today.

The current budget of $6.9 billion allots $2.5 billion for inmate programs, including $65.7 million for "psychology services," $115.5 million for drug treatment, and $435 million for food services.

"According to BOP officials, BOP’s biggest challenges are managing the continually increasing federal inmate population while providing for inmates’ care and safety, as well as the safety of BOP staff and surrounding communities, within budgeted levels," the GAO said. "BOP officials project continuing inmate population growth and estimate increases in funding needs for the foreseeable future."