? AN LUIS OBISPO, a city of about 7,000 people, is situated about midway between San Francisco and Los Angeles on the Southern Pacific Railway, some five miles south of Cuesta Pass through the main ridge of the Santa Lucia Mountains (Fig. 1). Towards the north and east is mountainous grazing country; a dairy farming district lies to the northwest; to the south is an area of general farming. The city owes a considerable portion of its activities to trade with the surrounding country, especially with the general farming district to the south and the dairying district to the northwest. Among the activities closely related to the conditions of the surrounding country, the retailing and wholesaling of supplies of all kinds are of great importance. There is also an important butter-manufacturing industry based upon the supply of cream from farms in nearby areas. San Luis Obispo is the seat of the county of the same name and therefore the center of local political and governmental activities. It is, furthermore, an important educational and recreational center. San Luis Obispo would not, however, have attained its present size and importance were it not for highly significant relationships to places and conditions many miles distant. The city is an important division point on the coast line of the Southern Pacific Railway, and has important car repair shops for that railroad. It is the headquarters of the Pacific Coast Railway, a narrow gauge line operating in a rich agricultural country between Port San Luis and Los Olivos in Santa Barbara County, which adjoins San Luis Obispo County on the south. The situation of San Luis Obispo near the coast on the route of a pipeline between oil fields in the San Joaquin Valley and Port San Luis, the shipping point for oil from those fields, has caused it to be an important local headquarters for the Union Oil Company. Finally, San Luis Obispo is located on the coast highway between San Francisco and Los Angeles, and has a considerable hotel business supported by tourists traveling between those cities. These varied activities have all contributed to the growth and importance of the city and they have operated to make it a place of interesting and varied relationships. In San Luis Obispo, the old and the new mingle. The flavor of the past centers around the old adobe mission (Fig. 2), once the center of the life of the settlement. A block from the mission, Chinatown, continues as the dilapidated remains of a larger Chinese settlement. Some of the houses of the old town close around the mission are constructed in part of adobe and are quaint reminders of the past. The new order is represented by modern hotels, large garages, stores and shops, electric lights, paved streets, and a beautiful residential district. I This study is part of a study of a larger area, a summary of which appeared in The Geographical Review under the title, Land Utilization in the Santa Lucia Region. (Geog. Review, Vol. XX, July, 1930, pp. 469-479.) The geography of San Luis Obispo is based almost entirely on field work done during the summer of 1925.