City classifications completed or proposed since the City Classification Handbook was published in 1972 are reviewed, and an alternative approach that links types of cities to technological premises and to long-term macrohistorical processes is proposed.In its charge to the author, the Office of Technology Assessment requested a report that (1) provided a brief overview of the intellectual history of city classification systems and how academics, planners, and others have used these systems; (2) summarized the principal classification systems that had been advanced to differentiate U.S. cities since the City Classification Handbook was published in 1972; (3) assessed how the various classification schemes discussed relate to one another; (4) developed a DOS-compatible spreadsheet database listing all U.S. metro areas and how the schemes offering actual classifications characterized them; and (5) offered suggestions for the development of classifications that link technological regimes and urban typologies in a consistent theoretical framework. Classification Systems for U.S. Cities attempted to respond to OTA's request. The purpose of this paper is to provide an overview of the report's conclusions and recommendations, particularly with respect to objectives (1), (2), and (5).Classification Systems began by pointing out that classifications seek out the order that exists within diversity: to classify is to believe that objects share common characteristics. Naming objects, and hence classifying them, is a fundamental feature of language. In this sense, classifications of settlements are part of everyday discourse. The similarities and differences present in urban hierarchies are captured by the distinctions between hamlets, villages, towns, cities, and metropolitan areas. A governmental hierarchy is implicit in the distinction between county seats and state capitals. Likewise, differences are captured by the distinctions between central cities, suburbs, and exurbs-yet another dimension of everyday differentiation that carries with it images of roles and functions. The purpose of more formal city classifications is, however, to go beyond everyday discourse. Social scientists strive to understand the causal processes that produce observed patterns; a first step is to reduce the patterns to a few manageable categories. Policymakers look for clues about the pathways to achieve specified goals, or about the consequences of different courses of action, turning either to the scientific understanding of causal processes or, failing that, to the lessons that may be learned from the experiences of "comparables."A number of efforts to provide a more systematic basis for understanding types of cities that might, in turn, improve urban policymaking and city management can be 674