The imprisonment rate skyrocketed as well. Back in 1978, 131 people per 100,000 were locked up. In 2012, 480 people per 100,000 are behind bars, more than a three-fold increase.
Here’s what that growth looks like, controlling for population, from our friends at @MetricMaps:
Some states stand out for massive explosions in prison populations. Arizona had just under 4,000 prisoners in the late 1970s. By 2012, 40,000 Arizonans were behind bars, a tenfold increase. Idaho went from 802 prisoners in 1978 to 7,985 in 2012, almost a 10 percent gain. Nevada and New Hampshire spiked nearly as high.
Every state saw its prison population at least double. On the lower end of the spectrum, Maine, Maryland, Michigan, New York, North Carolina and South Carolina all kept their prison populations under three times their levels in 1978.