Yep, it's pretty crazy. The US has the highest prison population in the world. In 2013, about 0.91% of adults (1 in 110) were in prison, with almost 2% (1 in 51) on probation or on parole. In total, 6,899,000 adults were under correctional supervision (probation, parole, jail, or prison) in 2013 – about 2.8% of adults (1 in 35). Madness!