Using US county data, we estimate employment growth equations to analyze how the spatial distribution of jobs has changed between 1972 and 2000. We find that total employment has become increasingly concentrated. This aggregate picture hides important sectoral differences though: whereas...

This paper studies the recent trends in the spatial distribution of economic activity in the United States. Using county-level employment data for 13 sectors - which cover the entire economy - we apply semi-parametric techniques to estimate how agglomeration and congestion effects have changed...