US Justice Department figures have shown the overall state and federal prison population stands at a record 2.3 million and is still rising.

One out of every 133 US residents is now in prison.

The biggest jump in incarceration figures was put down to immigration detainees, a third of whom originated from Mexico.

The population of prisoners has continued to edge up in all but 20 states, causing authorities to look for better and cheaper ways to deliver justice.

Politicians have realised prisons cost too much to maintain and are saving money with alternative sentencing programs, such as treatment or monitoring.

Officials released more prisoners during the year; some 735,454 prisoners.

Eight percent of those were pushed out without conditions.