Consumption Zones

Local area data are important to many economic questions, but most local area data are reported using political units, such as counties, which often do not match economic units, such as product markets. Commuting zones (CZs) group counties into local labor markets. However, CZs are not the most appropriate grouping for other economic activities. We introduce consumption zones (ConZs), groupings of counties appropriate for the analysis of household consumption. We apply the CZ methodology to payment card data, which report spending flows across U.S. counties for 15 retail and service industries. We find that different industries have different market sizes. Grocery stores have more than five times the number of ConZs as live entertainment. Industries with more frequent purchases are more local than those with infrequent purchases. We apply ConZs to measuring industry concentration. ConZs give lower concentration levels than counties, with the largest gap for infrequent purchase industries. The difference is economically important. Some industries are below the antitrust enforcement thresholds with ConZs but above them for counties. We further demonstrate the importance of ConZs by analyzing the proposed merger of Albertsons and Kroger.