O ver the past few decades, the United States has witnessed an enormous increase in the number of people in jail and in prison. As a response to surging crime rates in the 1960s and '70s, the nation got "tough on crime" stepping up policing, increasing arrests, and lengthening sentences producing hordes of new inmates. In 1979, around the time that imprisonment rates began their sharp uptick, the Bureau of Justice Statistics reported that 314,000 people sat behind bars in the United States. As of mid-2013, that number stood at about 2 million. Today, the United States has roughly 5% of the world's population and nearly a quarter of its inmates.
The evidence shows that this mass incarceration has performed more or less as advertised. By any measure, nearly every neighborhood, city, and state in the United States has become safer over the past two decades. Crime rates in many categories are at less than half of their all-time highs. But the costs of incarceration both financial and societal are also becoming increasingly clear. The policies that were appropriate for a nation that had one of the highest crime rates among developed Western countries are not necessarily appropriate for a nation that now has one of the lowest.