This study reveals that the average shopper, far from behaving at random, follows fairly distinct patterns. His habits are closely related to an ingrained feeling as to the convenience, range of merchandise, selection, and the service offered by a particular shopping area. There seems to be a set pattern, particularly with regard to the time that he shops, the frequency of shopping trips, the mode of travel used, and the shopping area he visits. A method has been developed whereby the destination and the frequency of auto transit shopping trips from any residential area can be predicted. The distribution of shopping-goods trips can be estimated by applying an adaptation of Reilly's law of retail gravitation, which uses automobile travel time as the distance factor and the retail floor area dedicated to apparel as the measurement of the size of the center.