Plant-level data from the Longitudinal Research Database of the US Bureau of the Census are employed to estimate the impact of agglomeration economies on industry productivity across US metropolitan areas. This analysis seeks to remedy three shortcomings of previous empirical studies of...

Change in evolutionary economics is predicated on the creative destruction of variety. Despite the importance of the concept of variety, or heterogeneity, in evolutionary economic theory, empirical work that examines the character of variety – its extent and its persistence – is still...