ArcGIS Living Atlas

Historical redlining data now in ArcGIS Living Atlas

This year’s User Conference was special. Not only was it the first ever virtual conference with a record number of attendees, but this year was also the inaugural year for the Equity and Social Justice track for user presentations. The virtual nature of this conference has given me the opportunity to see many user presentations. One topic that came up in many user presentations was redlining because of how valuable GIS-ready historical redlining data can be to help us understand how historical inequities still contribute to inequities today.

A redlining layer of 143 cities is now available in ArcGIS Living Atlas. This ready-to-use layer can provide important context for your work.

What is redlining?

The Home Owners’ Loan Corporation (HOLC) was created in the New Deal Era and trained many home appraisers in the 1930s. The HOLC created a neighborhood ranking system infamously known today as redlining. Local real estate developers and appraisers in over 200 cities assigned grades to residential neighborhoods. These maps and neighborhood ratings set the rules for decades of real estate practices. The grades ranged from A to D. A was traditionally colored in green, B was traditionally colored in blue, C was traditionally colored in yellow, and D was traditionally colored in red.

A (Best): Always upper- or upper-middle-class White neighborhoods that HOLC defined as posing minimal risk for banks and other mortgage lenders, as they were “ethnically homogeneous” and had room to be further developed.

B (Still Desirable): Generally nearly or completely White, U.S. -born neighborhoods that HOLC defined as “still desirable” and sound investments for mortgage lenders.

C (Declining): Areas where the residents were often working-class and/or first or second generation immigrants from Europe. These areas often lacked utilities and were characterized by older building stock.
D (Hazardous): Areas here often received this grade because they were “infiltrated” with “undesirable populations” such as Jewish, Asian, Mexican, and Black families. These areas were more likely to be close to industrial areas and to have older housing.
Banks received federal backing to lend money for mortgages based on these grades. Many banks simply refused to lend to areas with the lowest grade, making it impossible for people in many areas to become home owners. Home ownership is primary way that families build wealth in the United States.

The effects are still present today

While this type of neighborhood classification is no longer legal thanks to the Fair Housing Act of 1968 – passed in large part due to the activism and work of the NAACP and other groups – the effects of disinvestment due to redlining are still observable today. For example, the health and wealth of neighborhoods in Chicago today can be traced back to redlining (Chicago Tribune).
In addition to formerly redlined neighborhoods having fewer resources such as quality schools, access to fresh foods, and health care facilities, new research from the Science Museum of Virginia finds a link between urban heat islands and redlining (Hoffman, et al., 2020). This layer comes out of that work, specifically from University of Richmond’s Digital Scholarship Lab.

Use this layer in your work

This layer includes 7,148 neighborhoods spanning 143 cities across the continental United States. If you are involved in city projects examining neighborhoods, this layer can provide historical context of the neighborhood-level grades. Zoom in to your city, and combine this layer with your own data and make maps that visualize the spatial relationships by taking advantage of the many mapping styles that ArcGIS Online offers. Here are just a few ideas:
  • Symbolize it such that the only outlines show the color, letting your own data be the main focus.
Map of Stockton, CA with neighborhood polygons outlined in colors: green, blue, yellow, and red which correspond to their historical grade of A, B, C, and D, respectively.

An analyst from California Environmental Protection Agency (CalEPA) used this approach in a map shared in her presentation: “Addressing Environmental Justice Issues in Stockton, CA.” She displayed the intersection of historically redlined areas and present-day pollution indicators including hazardous clean-up sites, emissions, asthma, poverty levels, and others.

  • Apply a filter such that only the neighborhoods that received the lower grades (C and D) are displayed.
The filter dialogue box with the statement: "Display features in the layer that match any of the following expressions: HOLC_grade is C, HOLC_grade is D."

This approach is what an analyst at the city of Asheville, NC used and shared in her presentation: “Mapping Racial Equity in Asheville, North Carolina: A collection of maps about History, Displacement, and Neighborhood Change” when also showing recent displacement on the same map.

  • Summarize your own data by the four grades. Two analysts from the Seattle area summarized the average number of contaminated sites per square mile by these four grades. In their presentation, “Toward a Just, Green Future: Emerging Approaches for Equitable Public Investment,” they show how neighborhoods with the historical grade of “A” had an average of 17 contaminated sites per square mile in 2017, compared to 38 sites per square mile in neighborhoods that received a grade of “D.” Said another way, historically redlined neighborhoods in Seattle have more than double contaminated sites per square mile today than Seattle neighborhoods historically deemed the “best.”


Many organizations are interested in understanding present-day inequities in their communities. This layer represents a “fingerprint” of inequity from decades ago whose effects are still being felt today, which can help those in positions to advance equity and social justice. Your approach depends on what question you are trying to answer, and the ArcGIS platform provides many different symbology, filtering, and tabular data options to help you answer your research questions. In addition to the layer, an accompanying web map is available or those who just need a map to incorporate into a story map or dashboard. These are just two of the newest resources in ArcGIS Living Alas of the World: a collection of maps, apps, and data layers to support your work. You can also find additional resources and content on the Racial Equity GIS Hub. Share how you are using these resources, or post any questions you may have, on GeoNet’s ArcGIS Living Atlas and GIS for Equity and Social Justice spaces.

About the author

(she/her/hers) Diana loves working with data. She has over 15 years experience as a practitioner of demography, sociology, economics, policy analysis, and GIS. Diana holds a BA in quantitative economics and an MA in applied demography. She is a senior GIS engineer on ArcGIS Living Atlas of the World's Policy Maps team. Diana enjoys strong coffee and clean datasets, usually simultaneously.

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