ASPRS 2007 Annual Conference Tampa, Florida  May 7-11, 2007 URBAN SPRAWL METRICS: AN ANALYSIS OF GLOBAL URBAN EXPANSION USING GIS Shlomo Angel Robert F. Wagner School of Public Service, New York University Woodrow Wilson School of Public and International Affairs, Princeton University solly.angel@gmail.com Jason Parent and Daniel Civco Center for Land Use Education And Research (CLEAR) Natural Resources Management and Engineering University of Connecticut Storrs, CT 06269-4087 jason.parent@uconn.edu daniel.civco@uconn.edu ABSTRACT We define and present a comprehensive set of metrics for five dynamic attributes of urban spatial structure commonly associated with ‘sprawl’: (a) the extension of the area of cities beyond the walkable range and the emergence of ‘endless’ cities; (b) the persistent decline in urban densities and the increasing consumption of land resources by urban dwellers; (c) ongoing suburbanization and the decreasing share of the population living and working in metropolitan centers; (d) the diminished contiguity of the built-up areas of cities and the increased fragmentation of open space in and around them; and (e) the increased compactness of cities as the areas between their fingerlike extensions are filled in. We also introduce several metrics for key manifestations of sprawl. We present these metrics as well as actual calculations of these metrics for two cities: Bangkok and Minneapolis. A forthcoming paper will present similar results for a global sample of 120 cities. INTRODUCTION: THE ATTRIBUTES AND MANIFESTATIONS OF URBAN ‘SPRAWL’ A survey of this literature reveals an interesting dissonance. On the one hand, there is an almost universal consensus, with a few minor exceptions, on what are the key manifestations of sprawl: endless cities, fuzzy boundaries between city and countryside, a polycentric urban structure, ribbons and commercial strips, scattered development, and the fragmentation of open space, among others. On the other hand, there is the oft-repeated lament that sprawl⎯as an overarching characteristic common to all these manifestations⎯is ill defined and therefore difficult to measure using a single metric in a convincing way. This paper is a contribution towards the definition and the actual measurement of key attributes of urban expansion or ‘sprawl’ 1 . The paper has one central objective: to propose summary metrics for measuring these attributes, to define them, and to describe procedures for measuring them, given classifications of satellite imagery and population data for two time periods. The five attributes that have emerged as the key characterizations of urban sprawl in the literature and in our own investigations are: 1. The extension of the area of cities beyond the walkable range and the emergence of ‘endless’ cities; 2. The persistent decline in urban densities and the increasing consumption of land resources by urban dwellers; 3. Ongoing suburbanization and the decreasing share of the population living and working in metropolitan centers; 4. The diminished contiguity of the built-up areas of cities and the fragmentation of open space in and around them; and 1 The terms ‘urban expansion’ and ‘sprawl’ will be used interchangeably throughout this paper without necessarily attributing positive or negative attributes to these phenomena.