Today, the United States has just 5% of the world’s population but nearly 25% of the world’s prisoners. But it has not always been this way. Thanks to the “War on Drugs,” irrationally harsh sentencing regimes, and a refusal to consider evidence-based alternatives, the U.S. prison population grew by more than 700% between 1970 and 2009—far outpacing both population growth and crime rates.