Gentrification, on the surface, might be seen as a welcoming sight to urban areas, where previously low-income areas become transformed to higher income neighborhoods with a variety of associated benefits such as more varied and upscale stores, cleaner streets, safer neighborhoods, improved transport, and other benefits. However, the downside is it does displace lower income residents who were there previously, as rental and property costs, such as taxes, go up, leaving them unable to pay these increased costs. Effectively, gentrification can be seen as social cleansing in which neighborhoods push out lower income residents.
Given the phenomenon of gentrification happening in many cities across the United States in particular, more recently, municipal governments have begun using GIS to study the effects of gentrification. Initiatives have used publicly available data, such as Census data, to look at neighborhoods historically and estimate their change, in particular how gentrification has affected income and community makeup, and what areas may likely be affected in the future based on noticeable trends. One example city is Los Angeles, which has created a GIS database that is called the Los Angeles Index of Neighborhood Change using ArcGIS. This index measures education, income, race, rent, and household size as measures of gentrification across different city zip codes.
Portland was one of the first cities to use measures of gentrification and visualize the results publicly. These tools have been able to allow the city to track changes to Portland’s urban fabric. In the case of Portland, this tool allows future projections as well as an assessment of the current state by classifying gentrification, where the classes include: early gentrification with minor demographic change, early gentrification with more developed demographic change, dynamic gentrification, late-stage gentrification, and continued loss. These measures can represent stages of gentrification or where neighborhoods reach a given state.
Urban governments, in many ways, could be argued to have been prompted by community groups that began to use GIS in the 1990s to demonstrate the gentrification of their neighborhoods witnessed at around that time. The 1990s increasingly saw urban neighborhoods being “reinvigorated” through urban schemes intended to attract people back to cities, but this was often seen as a way to remove lower economic class residents for upper class residents. A good example of this was in San Francisco. Residents used what they called the ‘living neighborhood map’ to show how their once working-class district was changed to something they called ‘the Soho-ization’ of their urban neighborhood.
Gentrification can also occur when seemingly beneficial projects are placed in urban areas. More recent studies have shown that gentrification is often influenced by how cities react to potential influences of projects that can lead to an influx of more wealthier individuals to urban areas. Light rail has recently been constructed in a number of cities. In some places, this has exacerbated gentrification such as in San Francisco, while in other places, such as Portland, it has not shown any significant effect. Using a spatial regression model, researchers showed that it is conscious urban planning that counters any effects of gentrification that is what might be required to prevent improvement or infrastructure projects from leading to gentrification effects.
Other studies, using ordinary least squares regression, however, show it is more complex than the San Francisco and Portland results discussed earlier. It is not just urban policies but developers may target different parts of light rail projects for development. Thus, gentrification within cities could be localized to neighborhoods that are seen likely to benefit the most from the light rail, that is infrastructure project, development. This is the case for Portland. Simply stating counter gentrification policies work is not completely true, as some rail lines are seen as more beneficial for upper income residents and it is those lines that might become more gentrified.
Gentrification can be a major issue for municipal governments, where often lower income residents feel they might be displaced by urban policies that also try to invest and renew neighborhoods. The balance between urban development and gentrification is not straightforward, as seen in San Francisco and to some extent Portland. Cities are, however, as shown by Los Angeles and Portland, trying to now better understand gentrification through public and government-based GIS studying the effects of gentrifying factors.
 For more on Los Angeles gentrification index tool, see: http://www.govtech.com/data/Using-Mapping-to-Understand-Gentrification-Prevent-Displacement.html.
 For more, see Parker, C. & Pascual, A. (2002). A vice that could not be igrnored: Community GIS and gentrification battles in San Francisco. In: Community Participation and GIS, William J. Craig, Trevor M. Harris, Daniel Weiner (Eds.). Taylor and Francis: London and New York. Pp. 55-64.
 For more on how infrastructure projects in urban settings could affect gentrification, see: Baker, D. M., & Lee, B. (2017). How Does Light Rail Transit (LRT) Impact Gentrification? Evidence from Fourteen US Urbanized Areas. Journal of Planning Education and Research, 0739456X1771361. https://doi.org/10.1177/0739456X17713619.
 For more on differential aspects of gentrification and light rail, see: Rochester, Nathan. E. (2016). On Both Sides of the Tracks: Light Rail and Gentrification in Portland, Oregon. PhD dissertation. Portland State University. https://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=3923&context=open_access_etds
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