The decade of the 1970's has seen substantial improvement in our under standing of the determinants of urban spatial patterns. It is typical of western science and technology of the past several centuries that these advances in urban spatial analysis have resulted from the efforts of many individuals. No one of these claims to have found the answer; rather, each contributes some additional understanding of a rather complex set of inter related phenomena. All of this most recent work, in one way or another, rests on preliminary analysis work done in the previous ten to fifteen years. Those...