We estimate a model of urban productivity in which the agglomeration effect of density is
enhanced by a metropolitan area's stock of human capital. Estimation accounts for potential
biases due to the endogeneity of density and industrial composition effects. Using new
information on output per worker for US metropolitan areas along with a measure of density
that accounts for the spatial distribution of population, we find that a doubling of density
increases productivity by 2–4 percent. Consistent with theories of learning and knowledge …

We estimate a model of urban productivity in which the agglomeration effect of density is
enhanced by a metropolitan area's stock of human capital. Estimation accounts for potential
biases due to the endogeneity of density and industrial composition effects. Using new
information on output per worker for US metropolitan areas along with a measure of density
that accounts for the spatial distribution of population, we find that a doubling of density
increases productivity by 2 to 4 percent. Consistent with theories of learning and knowledge …