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Redlined, Now Flooding

Maps of historic housing discrimination show how neighborhoods that suffered redlining in the 1930s face a far higher risk of flooding today.

Flooding is a rising threat across the U.S., with homeowners facing as much as $19 billion in damages every year. What puts a neighborhood at high risk for flooding? Geography is key, but new data reveal another factor that can be determinative, too: race.

Contemporary maps for flood risk overlap in striking ways with New Deal–era maps used by the federal government to assess risk for mortgage lending. When appraisers mapped cities for the federal Homeowners’ Loan Corporation in the 1930s, they assigned grades to neighborhoods based on several factors, race high among them. Black and immigrant neighborhoods were deemed undesirable, marked by yellow or red lines designating these areas “declining” or “hazardous”—a racist practice known as redlining.

These historically redlined neighborhoods suffer a far higher risk of flooding today, according to new research from Redfin, the Seattle-based real-estate brokerage.

Using flood risk data from the nonprofit First Street Foundation and redlining maps from the University of Richmond’s Mapping Inequality project, Redfin assessed racial disparities in flood risk across dozens of major metro areas.

Consider Sacramento. The California capital region, with a population of more than 2 million, had the highest racial flood risk disparity in Redfin’s analysis.

For Sacramento, the greatest risk for flooding comes not from the city’s twin rivers but from its many creeks and distributaries.

In the 1930s, assessors praised Sacramento’s greenlined neighborhoods for their social homogeneity. Just one-third of the households in these areas today are non-white.

Appraisers redlined areas with racial minorities as undesirable for mortgage lending. Nearly half of the households in these neighborhoods are non-white.

Creeks in Sacramento have a high flood risk after strong downpours, with the highest risk in historically redlined neighborhoods.

Across 38 major U.S. metros, more than $107 billion worth of homes at high risk for flooding were located in historically redlined (and yellowlined) neighborhoods. That’s 25% more than the value of homes at high flood risk located in parts of the city deemed desirable—that is, white neighborhoods.

Put another way, 8.4% of homes in historically redlined neighborhoods face high flood risk nationwide, compared with 6.9% of homes in historically greenlined neighborhoods. These patterns reflect disparities in development compounded by decades of disinvestment.


Redlining's Effects on Public Health & Safety