The role of human capital in shaping cross-national economic performance is well-understood. But human capital is an indirect measure of skill, based on educational attainment. We introduce and test a more direct measure of skill, based on work that is actually performed, measured by occupation....

The prevailing geographic model for high-technology industrial organization has been the “nerdistan,” a sprawling, car-oriented suburb organized around office parks, of which Silicon Valley is the prototypical example. This seems to contradict a basic insight of urban theory, which...