At the turn of the 19th century, American universities were mostly under-resourced, regional schools. By World War II, they had become research leaders on the global stage, attracting the world's best scientists. In a paper in the Journal of Economic Perspectives, economists W. Bentley MacLeod and  Miguel Urquiola say that the US universities’ ascendancy in research started earlier than many people believe.  Just after the Civil War, two innovators found a successful formula. Johns Hopkins and Cornell made key reforms that started attracting the best research talent—and the large sums of money needed to keep it.  Today, reformers would like to tweak practices like tenure that helped create this virtuous circle. But Urquiola says they should keep a few important tradeoffs in mind. Urquiola recently spoke with the AEA’s Tyler Smith about the history of the US university system and what today's education policymakers can learn from it.