D L URING the last decade there has been marked improvement in the scope and refinement of urban studies undertaken by geographers. However, little attention has been given to urban land used for retail purposes, either as to structure or function in relation to city life. This exposition seeks to classify and characterize the principal types of city retail structure. It is based on a detailed study of Chicago, Philadelphia, Cleveland, Atlanta, and Des Moines, and a reconnaissance study of Washington, New York, Baltimore, and Knoxville. The principal cities of the United States, for the most part, possess five types of retail structure. These five types have been named: (1) the central business district; (2) the outlying business center; (3) the principal business thoroughfare; (4) the neighborhood business street; and (5) the isolated store cluster. These structural types are distinguished by: class of commodities sold; special concentration or dispersion of outlets; and character of customer tributary areas. The central business district represents the retail heart of each city (Figure 1). Here, individually and collectively, retail stores do a greater volume of business per unit area than elsewhere within the city. This areal concentration is manifested by the use of multistoried buildings of which retail stores, for the most part, occupy choice street level frontage, service establishments are concentrated into upper story offices, and residential occupance is restricted to scattered hotels. Here retail occupance is characterized by large department stores, numerous women's and men's clothing stores, furniture stores, shoe stores, jewelry stores, and similar outlets selling shopping goods. Added to these, though of subordinate importance, there are numerous drug stores, tobacco stores, restaurants, and other stores selling convenience goods (Figure 1 ). The central business district draws customers from all parts of the city proper and from outlying suburbs and nearby incorporated towns. Many people, besides being customers, are likewise employed in the various commercial and service occupations which constitute the complex of human activity within this district. To serve this movement of purchasing and working population to and from residential areas, all modes of intra-city transportation are focused here. This district, therefore, experiences extreme traffic congestion during the work-day and more particularly during the morning and late afternoon rush hours. The personal inconvenience of this congestion, and the commutation cost in time and money all have favored the development of the outlying business center, catering to the shopping goods wants of outlying population. The outlying business center represents, in miniature, the same type of retail structure characterizing the central business district. The center possesses a marked aerial concentration where closely spaced retail stores do a volume of business exceeded only by those of the central district. Here, for the most part, are found shopping goods outlets such as women's and men's clothing