The dynamics of industry agglomeration: Evidence from 44 years of coagglomeration patterns

Evidence abounds that agglomeration patterns have changed over time, but little is known about changes in the underlying determinants of agglomeration. We analyze 44 years of coagglomeration patterns of U.S. manufacturing industries and show that over time, input-output linkages and labor market pooling have become less important determinants of industry agglomeration, while knowledge spillovers have become more important. We show that trade and technology shocks are strongly associated with the decline in labor market pooling and the increase in knowledge spillovers. The downward trend in input-output linkages is associated with an increase in trade competition but not with a decrease in the transportation costs of goods.