Before theorizing gentrification, we must first define it. Gentrification is fundamentally a process of the class-upgrading of an area. Identifying the characteristics of this class upgrading is somewhat tricky; increases in home values, land values, income, educational status, and white residents are all key symptomatic and characteristic elements of gentrification. Direct real estate investment is another key characteristic, though it was not analyzed directly in this project. Many measures of gentrification place some sort of cut-off point for defining what neighborhoods are even gentrifiable—they must usually be below the median area values in terms of either income or home values. I find such a cut-point problematic, considering its arbitrary nature and its poor reflection of the colloquial or theoretical understanding of gentrification.
Some draw a distinction between gentrification and revitalization, asserting that the processes of reinvestment and gentrification are identifiable separate (Wentlandt 2003). I think such an assertion is theoretically muddled and obscures the ways in which municipal revitalization programs have equated to gentrification strategy. While it is true that displacement is a somewhat distinct (though closely related) phenomenon from gentrification, and may not always occur in a gentrifying area, erasing the distinction between revitalization and gentrification brings to the fore the class-nature of revitalization and questions of who is it meant for.
Gentrification theory can be broadly classified by the relative emphasis of supply side and demand side factors. Supply side gentrification theories (Smith and Williams 1996) explain the process as arising from broader dynamics of cyclical investment-disinvestment-reinvestment under capitalism. Gentrification is thus the “reinvestment” portion of the cycle, and consists of the exploitation of a rent gap (realized rents below potential rents) close to the center of a city. This rent gap was created during the “disinvestment” stage of the cycle, when a potent combination of structural racism and federally-subsidized suburbanization created large slums in the inner city. Industrial restructuring also plays a role here, with the offshoring of manufacturing creating vacuums of under-utilized brownfield space near the city core and on waterfronts. All this undervalued land provided profitable sites for eventual reinvestment.
Demand-side theories (Ley 1996; Hamnett 2000) are better represented in media coverage of gentrification. They emphasize the importance of more people wanting to live near the city center for various reasons (“return to the city” movement). Some theorize a rise of a creative class attracted to urban living and amenities. Structural factors also play a role in boosting demand for urban living. There’s been a dramatic decrease in crime from the 1980s to present, making the city more attractive to potential gentrifiers. Current demographics (the size of the Millennial generation and its tendency to put off family formation) also favor urban living. Traffic has generally worsened since the 1970s, making central living more attractive for those commuting to work downtown.
Richard Morrill (2000) created typology of gentrification, in which gentrification ‘A’ is characterized by mass scale public-private partnerships to densify and reinvest in the city core through the replacement of structures, institutions, and infrastructure. Gentrification ‘B’ conversely involves the more individually motivated (though still influenced by municipal policies like zoning designations, expansion of mortgage lending, or transit routing) decisions of professionals and other higher socioeconomic status groups to live near (though not necessarily in) the city center. This involves rehabilitation of structures and typically displacement of lower-socioeconomic status residents. Common gentrification discourse (and analyses conducted by the City of Portland and Governing) emphasizes the ‘B’ typology, focusing purely on residential change and ignoring the ways in which the strategic reinvestment in the core is inextricably linked to adjacent residential gentrification.
Transit can be related theoretically to gentrification through several means. Expansion of transit can intensify a rent gap by creating even higher potential land rents—this is especially salient where the service is actually useful in mobility terms and where driving is relatively unattractive. Transit can be seen as both an urban amenity itself and an indicator of the location of other amenities (as it’s most abundant in areas built before the automobile, when walkable neighborhoods and intermixed shops were the predominant mode of development). Both typologies of gentrification can furthermore be related to transit; ‘A’ gentrification frequently involves large, symbolic transit investments downtown (e.g. the Portland Transit Mall and light rail) to signify municipal commitment to the area. ‘B’ gentrification, meanwhile, frequently involves an influx of residents who work downtown, where transit access is generally attractive relative to car use.