Book excerpt: The evolving modern world is characterized by two opposing trends: integration and segregation. On the one hand, we witness strong forces for segregation on the basis of nationality, ethnicity, religion, and culture in the former Soviet Union, the former Czechoslovakia, the former Yugoslavia, as well as in Northern Ireland, Spain, and Canada. These forces are quite strong and, in some cases, violent. On the other hand, the European Union and NAFTA represent the tendency for integration motivated primarily by economic considerations (such as gains from trade and scale economies). In fact, these opposing trends can be explained by the concepts developed in modern club theory, local public finance, and international trade.