Private prison companies have helped fuel government policies which lead to an increase in prison population and boost their profits, according to a recent report.

The private prison population has grown 353.7 percent in the past 15 years, according to a study by the Justice Policy Institute. Major private prison companies have an incentive to encourage policies which keep that number on the rise.

“Steady increases in the number of people in private prisons, especially those coming from federally contracted beds, translate into increased revenues for private prison companies,” the report says.

“Since private prison companies are in the business to make money, policies that maintain or increase incarceration boost their revenues; from a business perspective, the economic and social costs of mass incarceration are ‘externalities’ that aren’t figured into their corporate bottom line,” it says.

Some of the biggest names in the private prison industry have given $835,514 to federal candidates since 2000 and a stunning $6,092,331 to state politicians in the last five elections cycles, according to data in the report.

“A lot of it is focused on the state level because a lot of the people in prison are in state facilities,” Paul Ashton, an author of the report, told TPM.

“With most states and the federal government operating under record deficits and decreasing budgets, private prison companies have a growing desire to establish influential connections with policymakers, with two goals: pitching private prisons as a lower cost alternative to building or maintaining state facilities; and fighting policies that might reduce the use of incarceration,” the report states.

The report also points to the revolving door between the private prison companies and the government agencies that have a say in their spending.

One recent example: Harley Lappin, who retired as head of the Bureau of Prisons after he was arrested for drunk driving, was recently named the chief corrections officer at the Corrections Corporation of America (CCA), the largest provider of private prisons to federal, state and local government. Lappin said in a press release announcing his new position that the company “has an outstanding track record of working well with its government partners as they strive to set the highest standards in the administration of a correctional system.”