THE INCREASING RETURNS REVOLUTION IN TRADE AND GEOGRAPHY
Prize Lecture, December 8, 2008 by Paul Krugman Princeton University, Woodrow Wilson School, Princeton, NJ 08544-1013, USA.

Thirty years have passed since a small group of theorists began applying concepts and tools from industrial organization to the analysis of international trade. The new models of trade that emerged from that work didn’t supplant traditional trade theory so much as supplement it, creating an integrated view that made sense of aspects of world trade that had previously posed major puzzles. The “new trade theory” – an unfortunate phrase, now quite often referred to as “the old new trade theory” – also helped build a bridge between the analysis of trade between countries and the location of production within countries. In this paper I will try to retrace the steps and, perhaps even more important, the state of mind that made this intellectual transformation possible. At the end I’ll also ask about the relevance of those once-revolutionary insights in a world economy that, as I’ll explain, is arguably more classical now than it was when the revolution in trade theory began. 1. TRADE PUZZLES In my first year as an assistant professor, I remember telling colleagues that I was working on international trade theory – and being asked why on earth I would want to do that. “Trade is such a monolithic field,” one told me. “It’s a finished structure, with nothing interesting left to do.” Yet even before the arrival of new models, there was an undercurrent of dissatisfaction with conventional trade theory. I used to think of the propagation of this dissatisfaction as the trade counterculture. There were even some underground classics. In particular, Staffan Burenstam Linder’s An Essay on Trade and Transformation (1961), with its argument that exports tend to reflect the characteristics of the home