UR approach to this study in urban geography is threefold: selection of those cities of United States that are metropolitan; delimitation of regions served by them in various functional capacities; delimitation of composite regions and interpretation of functions of cities in relation to economic character of regions they serve. First, however, concept metropolitan must be defined, for term is unfortunately often used as vaguely expressing quality of a large city. The 1930 census of United States defines a district as an urban unit having an aggregate population of 00oo,ooo or more, and containing one or more central cities of 50,000 or more inhabitants, and recognizes 96 such districts.1 Only a few of these, however, are according to our definition as already applied to cities of England and Wales.2 Accepting definition of economy as the organization of producers and consumers mutually dependent for goods and services, wherein their wants are supplied by a system of exchange concentrated in a large city which is focus of local trade and center through which normal economic relations with outside are established and maintained,3 a city becomes most kinds of products of district concentrate in it for trade as well as transit; when these products are paid for by wares that radiate from it; and when necessary financial transactions involved in this exchange are provided by it.4 Such a city will have a population considerably larger than that of surrounding towns; it will be an independent center of trade, with a large variety of regional industries and a large wholesale business; it will be a financial center and finally a cultural and administrative center. It does not follow that integration is always in one center, however, for frequently two or more cities, serving same region, subdivide sum of functions.