Many new technologies display long adoption lags, and this is often interpreted as evidence of frictions inconsistent with the standard neoclassical model. We study the diffusion of the tractor in American agriculture between 1910 and 1960-a well-known case of slow diffusion-and show that the...

We reevaluate the role of human capital in determining the wealth of nations. We use standard human capital theory to estimate stocks of human capital and allow the quality of human capital to vary across countries. Our model can explain differences in schooling and earnings profiles and...