Using microlevel commodity flow data and microgeographic plant-level data, we construct
industry-specific ad valorem trucking rate series and measures of geographic concentration
to provide evidence on the relationship between transport costs and agglomeration. We find
that low-transport-cost industries display significantly more geographic concentration in the
cross-sectional dimension and that falling transport costs agglomerate industries in the
panel dimension. The effects are large: the fall in trucking rates between 1992 and 2008 …

Using micro-level commodity flow data and micro-geographic plant-level data, we construct
industry-specific ad valorem trucking rate series and measures of geographic concentration
to provide evidence on the relationship between transport costs and agglomeration. We find
that low transport cost industries display significantly more geographic concentration in the
cross-sectional dimension, and that falling transport costs agglomerate industries in the
panel dimension. The effects are large: the fall in trucking rates between 1992 and 2008 …