In the second of two parts of a conversation about the U.S.-Mexico border wall that President Trump has pledged to build, Brookings Senior Fellow  discusses the costs of a wall for the U.S. economy and the environment, and whether it would have any effect on crime and violence. Also in this episode, meet Jay Shambaugh, new director of the Hamilton Project at Brookings. Subscribe to Brookings podcasts  or on , send feedback email to , and follow us and tweet us at  on Twitter. The Brookings Cafeteria is a part of the .