Before revision:  In closing, we examine historical data on interstate wars and trade, noting that a dramatic (more than ten-fold) drop in the rate of interstate wars since 1950 is paralleled by the advent of nuclear weapons and an unprecedented growth in trade over the same period, matched with a similar densification and stabilization of alliances,  consistent with the model  .
After revision:  In closing, we examine historical data on interstate wars and trade, noting that the dramatic drop in interstate wars since 1950 is paralleled by the advent of nuclear weapons and an unprecedented growth in trade over the same period, matched with a similar densification and stabilization of alliances, consistent with the model .