Contents lists available at ScienceDirect Land Use Policy journal homepage: www.elsevier.com/locate/landusepol Suburbia in evolution: Exploring polycentricity and suburban typologies in the Seoul metropolitan area, South Korea Hyungkyoo Kim a , NaYeon Lee b , Seung-Nam Kim c, ⁎ a Department of Urban Design and Planning, Hongik University, 94 Wausan-ro, Mapo-gu, Seoul, 04066, South Korea b Graduate School of Environmental Studies, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea c Department of Urban Design and Studies, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, South Korea ARTICLE INFO Keywords: Suburb Polycentricity Edge cities Boomburbs Seoul metropolitan area ABSTRACT The transformation of the Seoul Metropolitan Area (SMA), South Korea, is relatively unknown despite the rapid suburbanization that has occurred since the late twentieth century. This study examines the area and its evo- lution between 1985 and 2015. It finds increasing levels of polycentricity in the SMA measured with five indices. With a refined set of metrics, it identifies nine Edge Cities and eight Boomburbs in the SMA that operate as new suburban centers of growth in the area, as well as several types within them. The evolution of the SMA is largely due to the active role of the state in implementing regional planning, as well as the autonomous actions of private companies and citizens. These result in a unique suburban landscape that differs from those of Europe and the US. This study suggests the need for further research on the SMA in search of new models and concepts that theorize new transformations that metropolitan areas experience. 1. Introduction Metropolitan areas in Asia are generally recognized as highly po- pulous and dense parts of the world that undergo rapid growth and expansion. Demographia (2017) places eight of them among the top ten most populous ones in the world and nine among the top ten densest. A Brookings essay by Trujillo and Parilla (2015) identifies six from Asia among the world’s ten fastest-growing metropolitan areas. However, not much is known about these Asian metropolitan areas, other than their outside appearances that are illustrated by indicators and argu- ments on social and environmental challenges they may experience (Douglass, 2000; McGee and Robinson, 2000; Singh, 2015; Sorensen and Okata, 2011). Urban scholars may be more familiar with the decades of debates on metropolitan structures and suburbs that are mainly based on the European and American experiences (Fishman, 1987; Hayden, 2004). European and American cities have gone through suburbanization since around a century ago, and there are a series of concepts and ideas that have fructified, which can be largely grouped into two approaches. One is polycentricity, which is defined as the existence of multiple centers, as opposed to a monocentric urban area that has a sharp divide between city and suburban hinterland (Kloosterman and Musterd, 2001). In recent decades, Hall’s (1984) description of Randstad as a polycentric metropolitan area sparked further studies on polycentricity and its diverse aspects in many European urban regions (Davoudi, 2003; Hall and Pain, 2006). They include the usefulness of poly- centricity as a planning concept (Bailey and Turok, 2001; Houtum et al., 2001), building regional capacity (Meijers and Romein, 2003), synergy and networks (Burger et al., 2014; Kloosterman and Lambregts, 2001; Meijers, 2005), increasing commuting distances (Aguilera, 2005), inter-city relations in industry (Hanssens et al., 2014; Taylor et al., 2009), and measurement issues (Meijers, 2008; Veneri and Burgalassi, 2012). A second approach comes from the American suburbanization ex- perience which has established new typologies for suburbs or me- tropolitan areas (Duany et al., 2000; Hayden, 2004; Jackson, 1985). Some of the recent examples include Edgeless City (Lang, 2003), Me- troburbia (Knox, 2008), the New Metropolitan Reality (Hanlon et al., 2010), and Megapolitan Areas (Nelson and Lang, 2011). Two typologies that enjoy substantial popularity may be Edge City by Garreau (1991), which paid attention to concentrations of office and retail, but less so to residential areas, outside traditional urban centers, and Boomburb suggested by Lang and LeFurgy (2007) as a sizable suburban city, but not the core city of the region, that has shown rapid growth. The two approaches are not at all exclusive to their birthplaces and have been exchanged. The polycentricity concept is applied in studying American metropolitan areas (Cervero and Wu, 1997; Giuliano and Small, 1991; Gordon and Richardson, 1997, 1996; Hajrasouliha and https://doi.org/10.1016/j.landusepol.2018.03.033 Received 3 November 2017; Received in revised form 8 February 2018; Accepted 13 March 2018 ⁎ Corresponding author. E-mail addresses: hkkim@hongik.ac.kr (H. Kim), dlsk3336@snu.ac.kr (N. Lee), snkim@cau.ac.kr (S.-N. Kim). Land Use Policy 75 (2018) 92–101 0264-8377/ © 2018 Elsevier Ltd. All rights reserved. T