Knowledge flows within and across countries should be carriers of important learning spillovers. We use data on 1.5 million patents and 4.5 million citations to analyze knowledge flows across 147 subnational regions. We estimate that only 15% of average knowledge is learned outside the average...

Identification of the strength of human capital externalities at the aggregate level is still not fully understood. The existing method may yield positive or negative externalities even if wages reflect marginal social products. We propose an approach that yields positive average human capital...

After a decade in which wages and employment fell precipitously in low-skill occupations and expanded in high-skill occupations, the shape of U.S. earnings and job growth sharply polarized in the 1990s. Employment shares and relative earnings rose in both low and high-skill jobs, leading to a...