Segmentation of consumer markets in the US: What do intercity price differences tell us?

We quantify the magnitude of market segmentation in US consumer market and explore the underlying factors behind this segmentation, using a quarterly panel of retail prices for 45 products in 48 US cities from 1985 to 2009. The extent of market segmentation is estimated using city-pair price differences within the framework of both linear autoregressive (AR) and nonlinear threshold autoregressive (TAR) models. We find that the magnitude of market segmentation varies from one product to another, but even more across city pairs in each product. Contrary to a widespread perception, market segmentation within the US is not necessarily larger for non-tradable services compared to tradable goods. We identify potential drivers of market segmentation by relating the cross-city and cross-product variations of market segmentation to location-specific and product-specific characteristicsdistance, relative city sizes, differences in wage and rent, type of product and proximity to marketplace. Distance, which captures more than transport costs, turns out to be the most salient factor even after controlling for a range of other potential factors. The effect of distance, however, varies substantially across products, with perishable products and locally produced products showing larger distance effect on market segmentation. We find that the magnitude of market segmentation has been somewhat stable during the sample period, but intercity price differences have become more sensitive to distance over time in many products under study.