This essay relates recent developments in growth theory to problems and ideas that first engaged R. F. Harrod, E. Domar, and their neoclassical successors. The body of 'new growth theory' began by finding special ways to assume that there are constant returns to capital. It is shown that this is...

International productivity comparisons can be built up with micro and macro data. Studies of firms or groups of firms producing similar outputs reveal the deeper causes of differences in productivity across countries. The studies find that such differences often depend on patterns of...

The traditional model of the equilibrium economic geography of a monocentric city is generalized to introduce congestion costs as well as distance costs of the transportation. This has the effect of generating more curvature in the equilibrium rent gradient than the early theory had suggested....

This brief retrospective note describes the author’s occasional contributions to the economics of natural resources. It emphasizes the role and interpretation of the Hotelling condition and discusses the reasons why that result plays so small a role empirically. The concept of sustainability...