To explain the large differences in labor productivity across U.S. states, the authors estimate two models--one based on local geographical externalities and the other on the diversity of local intermediate services--where spatial density results in aggregate increasing returns. Both models lead...

The credibility of temporary protection is examined in a simple infinite horizon, perfect information game of timing in which the domestic government uses the threat of future liberalization to induce the domestic firm to invest. All pure strategy subgame-perfect equilibria are cyclical and,...

We develop a simple macroeconomic model of credit market imperfections with heterogeneous investment projects. The projects differ in productivity, the investment requirement, and the severity of agency problems behind the borrowing constraints. A movement in borrower net worth shifts the...