As The Economist went to press, Barack Obama was scheduled to travel to El Reno in Oklahoma, thus becoming the first sitting president to visit a federal prison. The trip is a sign of how far the politics of punishment have changed. Up until recently most Democrats were wary of looking any softer on crime than Republicans. Now it is almost orthodox in both parties to say that America, which has less than 5% of the world’s population and almost 25% of its prisoners, locks up too many people. Yet the limits of what a president can do are clear: most of the imprisoning in America is done by the states. Many of the governors now running for president are taking stands on prison reform. The chart below shows what they actually did while in office.