The industries with the highest localization arc not, as expected, those with large plants, but are those with medium scale plants. Certainly the large scale plants are more localized than the small scale, but the outstanding cases of high localization—cotton textiles, woollen textiles, motor-car manufacture—are characterized in general by medium scale plants gable 5.11). This high localization in one industry may well be due to the fact that the plants between themselves form a single, large, localized producing unit. The difference is that, whereas in the large single plant the economies are internal, in the localized 'swarm' of plants the economies are external