We derive a simple equation for the welfare gains from trade when tariffs are liberalized or iceberg trade costs fall. Covering various one-sector trade models that may or may not feature extensive margins and imperfect competition, we generalize the analysis of Arkolakis, Costinot and...

All countries would agree to immediate global free trade if countries were compensated for any terms-of-trade losses with transfers from countries whose terms-of-trade improve, and if customs unions were required to have no effects on non-member countries. Global free trade with transfers is in...

We review a recent body of theoretical work that aims to put numbers on the consequences of globalization. A unifying theme of our survey is methodological. We rely on gravity models and demonstrate how they can be used for counterfactual analysis. We highlight how various economic...

<span><span style=""font-style:italic;"">John Maynard Keynes: Free Trader or Protectionist?</span><span> sheds light on Keynes' position on the issue of free versus protected international trade. Over his lifetime, Keynes' position altered from free to restricted trade, and quite possibly back to his original position by the end of his career....</span></span>

Firms play a critical role in the global economy. In this paper, we survey the behavior of firms in the international economy, both in theory and in the data. We first summarize the key empirical facts that motivate the study of firms in trade. Then, we detail recent theoretical developments on...