Dwindling oil revenues in Oklahoma are spurring a nowadays rare collaboration by state politicians of all stripes on reforming a bulging prison system that critics say is in danger of breaking down.

The state, always an oil producer, cashed in on the massive growth of fracking operations that extracted hard-to-reach crude oil, boosting tax revenues and easing fiscal constraints.

But the collapse in oil prices in 2014 contributed to a massive US$1.3 billion budget deficit, bringing into focus the state's overcrowded and costly corrections system.

As revenues plummeted, the correctional system's US$500 million in annual costs continued to escalate, raising questions about the effectiveness of the "tough on crime" stance the state has taken for decades.

The state's tough-on-crime ethos has spurred the second-highest overall incarceration rate in the country, with a prison system running at 122 percent of capacity. That makes it the third-most-overcrowded in the country, according to the DOC.

Voters will decide in November whether to support initiatives to reclassify low-level drug and theft offenses as misdemeanors and direct money to drug rehabilitation and mental health programs.