Tyler Cowen apparently believes that building a wall along our southern border (part of my ideal immigration policy) is pointless because it's easy to forge the documents needed to get through a guarded U.S. border checkpoint. Cowen knows plenty more about Mexico than I do, and I don't dispute his claim that illegal papers are a a "major channel" of illegal immigration (though an order-of-magnitude quantification of "major" and/or the price of illegal papers would be appreciated). However, I expect illegal papers to become a lot more expensive in a few years.