New Map Feature: Redlining

The Dashboard is excited to announce that historic redlining maps for 364 Dashboard cities are now accessible on the “Metric Detail” page for any metric. Redlining refers to a practice of grading the financial risk of providing home loans based on the characteristics and location of the neighborhood. Redlining was common practice in the United States in the 1930s and 1940s and was not outlawed until 1968.

What do the Maps Represent?

The Homeowners Loan Corporation (HOLC) was established in 1933 to stabilize the housing market during the Great Depression. As part of doing so, HOLC created color-coded maps for over 200 cities (population > 40,000 when the maps were drawn) to portray perceived mortgage lending risk. These maps assigned city neighborhoods with letter grades: "A" (map colored green) for the safest investment and "D" (map colored red) for the highest risk. The red color for D grades is where the term “redlining” comes from. While HOLC cited housing quality and sales trends as primary factors, racial and ethnic composition heavily influenced the ratings. Predominantly Black and immigrant neighborhoods were routinely redlined (Mallach 2024; Michney 2022).

The Federal Housing Administration (FHA), a related federal agency established in 1934, also developed its own mortgage lending risk assessment that often-mirrored HOLC classifications (Aaronson et al. 2021). Only a handful of the FHA maps are available today; therefore, HOLC maps are the most comprehensive record of this era’s redlining practices. The Dashboard team accessed the HOLC map boundaries now presented on the City Health Dashboard website from the Mapping Inequality project (Nelson et al. 2023).

How to Access the Maps

When viewing a metric map on the “Metric Detail” page of the City Health Dashboard, you can scroll down to the “Redlining Map” icon on the bottom left of the map screen. Once you select the icon, a box will pop up with information about the maps and with the option to select various redlining grades; however, the default setting will have all grades selected and presented within city boundaries. Due to shifts in city boundaries since the maps were first drawn, many cities won’t have all grades available. You can toggle each grade on and off. It is important to note that upon opening the Redlining Map, the metric map information will be turned off. To return to the metric map, you can simply exit the redlining box.

How to Interpret Redlining Maps

HOLC maps are a powerful visual reminder of how race and class shaped access to housing and financial opportunity in the U.S. They’re also one piece of a larger story. Some research suggests that the HOLC maps didn’t directly cause federal or private lending discrimination—many neighborhoods labeled high-risk were already facing disinvestment due to racist banking practices and segregation laws. Scholars also point out that other forces, like the growth of suburbs, urban renewal, and White flight, played major roles in deepening racial and economic divides (Markley 2023; Gioielli 2022; Fishback et al. 2021; Mallach 2024; Swope et al. 2025). Even with these caveats, though, the HOLC maps contributed to real-world consequences. Redlined areas were more likely to experience declining home values, reduced homeownership, and less investment over time — all of which had long-term effects. Recent research has linked redlined neighborhoods to present-day gaps in health outcomes, life expectancy, school quality, and environmental risks (Aaronson et al. 2021; Xu 2023; Graetz & Esposito 2023).

These maps help visualize how racialized policy shaped city landscapes. While HOLC maps do not fully explain today’s health and economic disparities, they offer important insight into how historic disinvestment patterns took root.

Important Data Considerations

Adding these HOLC boundaries to the existing Metric Detail user experience as a supplementary mapping feature is a first for the City Health Dashboard website. The process to bring these maps to life has been several years in the making and required much research and development by the Dashboard team to understand and overcome the challenges of including historical maps on a digital, interactive platform that presents current city boundaries. Maintaining the broad accessibility of the Dashboard user experience was paramount when developing this new feature, and there are important things to consider when viewing a city’s redlining maps.

1. Not all Dashboard cities have HOLC maps since the original 1930s project only focused on ~ 200 large cities/areas.

2. We are able to provide maps for 364 cities because some of the original HOLC maps were created for larger counties or regions. For example – the Los Angeles region has a single HOLC map, but over 12 present-day cities are covered by the HOLC grades from that original Los Angeles map and will therefore have redlining maps on the Dashboard.

3. Only a small portion of many cities’ current boundaries are covered by redlining maps due to shifts in city boundaries since the maps were drawn and because some cities are on the edges of originally redlined areas.

4. Many cities won’t have all grades (A-D), because their current city boundaries are covered by only a small portion of an originally redlined area.

Citations

1. Aaronson, D., Hartley, D., & Mazumder, B. (2021). The Effects of the 1930s HOLC “Redlining” Maps. American Economic Journal: Economic Policy, 13(4), 355–392. https://doi.org/10.1257/pol.20190414

2. Fishback, P. V., Rose, J., Snowden, K. A., & Storrs, T. (2021). New Evidence on Redlining by Federal Housing Programs in the 1930s (Working Paper No. 29244). National Bureau of Economic Research. https://doi.org/10.3386/w29244

3. Gioielli, R. (2022, November 3). The Tyranny of the Map: Rethinking Redlining. The Metropole. https://themetropole.blog/2022/11/03/the-tyranny-of-the-map-rethinking-redlining/

4. Graetz, N., & Esposito, M. (2023). Historical Redlining and Contemporary Racial Disparities in Neighborhood Life Expectancy. Social Forces, 102(1), 1–22. https://doi.org/10.1093/sf/soac114

5. Mallach, A. (2024a). Shifting the Redlining Paradigm: The Home Owners’ Loan Corporation Maps and the Construction of Urban Racial Inequality. Housing Policy Debate, 34(6), 891–917. https://doi.org/10.1080/10511482.2024.2321226

6. Mallach, A. (2024b, August 21). Redlining Maps Didn’t Affect Neighborhoods the Way You Think They Did. Shelterforce. https://shelterforce.org/2024/08/21/redlining-maps-didnt-affect-neighborhoods-the-way-you-think-they-did/

7. Markley, S. (2024). Federal ‘redlining’ maps: A critical reappraisal. Urban Studies, 61(2), 195–213. https://doi.org/10.1177/00420980231182336

8. Michney, T. M. (n.d.). Mapping Inequality. Retrieved March 25, 2025, from https://dsl.richmond.edu/panorama/redlining/

9. Michney, T. M. (2022). How the City Survey’s Redlining Maps Were Made: A Closer Look at HOLC’s Mortgagee Rehabilitation Division. Journal of Planning History, 21(4), 316–344. https://doi.org/10.1177/15385132211013361

10. Nelson, Robert K., LaDale Winling, et al. “Mapping Inequality: Redlining in New Deal America.” Edited by Robert K. Nelson, American Panorama: An Atlas of United States History, 2023, dsl.richmond.edu/panorama/redlining.

11. Swope, C., Markley, S., Whittaker, S., & Hillier, A. (2025). How and Why Does Redlining Matter for Present-Day Health? Critical Perspectives on Causality, Cartography, and Capitalism. American Journal of Public Health, 115(5), 769–779. https://doi.org/10.2105/AJPH.2024.308000

12. Xu, W. (2023). Where Did Redlining Matter? Regional Heterogeneity and the Uneven Distribution of Advantage. Annals of the American Association of Geographers, 113(8), 1939–1959. https://doi.org/10.1080/24694452.2023.2205514Appendix