No abstract

IntroductionAn assertion that the majority of the world's people live in informal housing would not be far off the mark. One estimate, by now over a decade and a half old, held that 40% of the total population of the developing world's major cities lived in extra legal conditions (Fernandes and Varley, 1998). Not surprisingly, an enormous and con stantly growing trove of scholarship has grappled with informal housing in its myriad regional variations for more than half a century (Gilbert and Ward, 1985;Farvacque and McAuslan, 1992; de Soto, 2000). However, few such accounts or official policy documents deal with informal housing in the global North in general or the United States in particular. For instance, UNHabitat's 2012-2013 State of the World's Cities report omits industrialized nations altogether from its countrybycountry tally of the number of people worldwide living in slum conditions (UNHabitat, 2013: 148-49). Similarly, Arnott (2009: 169), quoting data from Angel (2000), reports that 'high income countries', including the US, have a zero per cent share of unauthorized (that is, informal) housing.Informal housing in the US is also absent from domestic discussions of housing policy. For instance, in three highly regarded books on US housing policy published in the past decade there appears not a single reference to housing informality (Bratt et al., 2006;Retsinas and Belsky, 2008;Schwartz, 2010). In this article, we call attention to the blind spot in informal housing in USfocused housingrelated scholarship. We contend that although informal land and housing markets in places such as suburban Los Angeles or periurban El Paso do not physically resemble their irregular settlement counterparts in the favelas of Rio de Janeiro or the bidonvilles in Algiers, they are nonetheless prevalent and pose considerable challenges to planners, policymakers and local governments in the US. Here, we seek to map the landscape of informal housing research in the US, and in doing so highlight what we know, what we have yet to learn and what the critical questions are on which future research should focus.We wish to thank Peter M. Ward for reviewing and providing comments on an earlier version of this article. We are also grateful to the three anonymous IJURR reviewers for their challenging and insightful comments. INFORMAL HOUSING IN THE UNITED STATES 283Scholarly interest in various types of informal economic activities in the US, such as manufacturing (SassenKoob, 1994), casual labor (Valenzuela, 2003) and street vending (Duneier and Carter, 1999), extends back several decades and continues to deepen as a result of recent indepth analyses of informality in a variety of sectors (see Richardson and Pisani, 2010, as well as an edited volume by Mukhija and Loukaitoi Sideris, 2014). Meanwhile, other scholarship has described various instances of infor mal housing but, besides several notable and mostly recent exceptions (Ward, 1999;Larson, 2002;Mukhija, 2014), has not explicitly engaged with informality as a theo retical conc...

Secondary units, or separate small dwellings embedded within single-family residential properties, constitute a frequently overlooked strategy for urban infill in high-cost metropolitan areas in the United States. This study, which is situated within California's San Francisco Bay Area, draws upon data collected from a homeowners' survey and a Rental Market Analysis to provide evidence that a scaled-up strategy emphasizing one type of secondary unitthe backyard cottagecould yield substantial infill growth with minimal public subsidy. In addition, it is found that this strategy compares favorably in terms of affordability with infill of the sort traditionally favored in the 'smart growth' literature, i.e. the construction of dense multifamily housing developments.

No abstract