Gini coefficients are calculated for the geographic concentration of employment in U.S. manufacturing industries. The theoretical reasons for clustering are discussed. It is found that manufacturing industries that are greatly involved in international trade are more geographically concentrated than those that are not, with export-sensitive industries generally located in different regions than import-sensitive industries. Export-sensitive industries are concentrated in the Pacific region while import-sensitive industries are concentrated in the Atlantic region; industries that are both import and export sensitive are in the Great Lakes region. Geographic concentration is also positively related to average establishment size and negatively related to the overall number of establishments. It is also found that trade-related displacements are more geographically concentrated than manufacturing employment.