Heat and Housing: A Link between Historic Racism and Current Environmental Inequities

On July 29, 2009, the temperature reached a sweltering 103 degrees at Seattle-Tacoma airport. Brutal temperatures persisted for three days, and two people in Western Washington died. Seattle is one of the fastest growing cities in the U.S., partly because of its famously temperate weather consisting of cool, wet winters and mild summers. However, it is this mild climate that makes extreme heat even more dangerous when it occurs. In 2015, only one-third of housing units in Seattle’s metropolitan area had air-conditioning. As global temperatures increase due to human-driven climate change, heat waves will increase in frequency, and the time between such events will become shorter. Of the country’s 15 most populous cities, Seattle ranks fourth-highest in number of deaths projected from heat waves for every 100,000 residents.

Bar graph showing weather-related fatalities in 2018
Tornadoes and hurricanes garner visceral fear and abundant media attention, but heat causes more fatalities than any other weather event, according to NOAA’s natural hazard statistics.


Heat waves in Seattle are intensified by the heat island effect. Urbanization alters a landscape; it replaces open land and vegetation with buildings, roads, and other infrastructure and transforms the area into one with impermeable, dry surfaces. These changes cause urban areas to become warmer than their rural surroundings, creating an “island” of hotter temperatures. Additionally, it has been shown that vulnerable communities, particularly those of color, are disproportionately exposed to extreme heat. Race has been linked to heat-related disasters, like the 1995 heat wave in Chicago that led to more than 700 deaths of mostly elderly African-Americans in just five days. Cities have been planned and financed around racial discrimination, so what if intra-urban heat inequity can also be directly tied to historical housing policies?


In the 1930’s, in a bid to lift the U.S. out of an economic recession, the Home Owners’ Loan Corporation (HOLC) instituted a racist practice called “redlining,” where HOLC refinanced mortgages at low interest rates to prevent foreclosures. In this process they created color-coded residential maps ranking neighborhoods from “best” to “hazardous” for real estate investment, largely based on racially motivated ideas surrounding safety. The most hazardous were outlined in red, hence the name “redlining.” Subsequently, banks and lending institutions in redlined neighborhoods would refuse home loans or require higher interest rates and larger down payments predominantly for minorities interested in purchasing a house in these areas. This practice systemically encouraged disinvestment and lower property values, which meant these neighborhoods would become more affordable for people of color who were also excluded from higher paying jobs. Meanwhile, white people could afford better neighborhoods, which further exacerbated existing segregation.

A pink cover of a brochure "Redlining and Disinvestment in Central Seattle: Now the Banks are Destroying Our Neighborhoods"
Even though redlining was implemented in the 1930s, it took decades for the practice to be recognized as faulty and racist.


Although the practice came to be banned with the implementation of the federal 1968 Fair Housing Act, it left a legacy of racial disparities in health care, access to healthy food, incarceration, resources allotted for schools, and public infrastructure investment. Redlining affected all major U.S. cities, including Seattle. By dividing Seattle based on “grade of security,” the city directed public and private capital to native-born white families and away from African-American and immigrant families. Redlining practices were particularly impactful in the Central District and Rainier Valley, and the ratio of deposits to loans in the Central District branch banks was 24%, while the ratio was 97% in suburban branch banks. This practice meant that far fewer account holders in the historically African-American Central District neighborhood qualified for loans than in suburban, whiter areas. Racial restrictive covenants served as a way to restrict the sale or rental of property to certain groups. For example, clauses like “[n]o person or persons of Asiatic, African or Negro blood, lineage, or extraction shall be permitted to occupy a portion of said property” can still be found in the deeds of many Queen Anne homes.


A color coded map of the city of Seattle
An appraiser for the Home Owners’ Loan Corporation created this map on January 10th, 1936. This image comes from Mapping Inequality, an effort to bring these historic maps into the digital age to tell the story of how an eight decades-old practice has contributed to wealth inequalities we still see today. Additionally, the Wing Luke Museum currently has an exhibit about redlining for more information about Seattle’s history of redlining. Source: Nelson, R.K.; Winling, L, 2020.


In a recent study, researchers from the Science Museum of Virginia performed a spatial analysis to explore the relationship between redlining and intra-urban land surface temperature anomalies. They studied 108 U.S. urban areas and found that 94% of the study area showed consistent patterns of elevated surface temperatures in formerly redlined areas compared to their non-redlined neighbors by as much as 7°C. In Seattle, areas labeled as “best” are 1.45°C cooler than the city’s average temperature, while areas labeled “definitely declining,” like the Rainier Valley neighborhood, are 0.90°C warmer than average. Although these differences seem minimal and likely less pronounced than other U.S. cities due to differing topography and environmental patterns, the legacy of redlining has still contributed to a racial “green gap” in Seattle.

These side-by-side images show the tight segregation of Seattle in the 1960s, the decade when the Fair Housing Act was passed. The left shows the percentage of African Americans within each census tract, and the right shows the percentage of Asian American and Pacific Islanders. Nearly all members of these minority groups are locked in a triangle of census tracts in the Central District and Chinatown. Compare this to a map of hyper-local temperatures in Seattle measured in June 2017.


Housing discrimination significantly limited real estate investment, which often means that redlined areas have fewer environmental amenities like green spaces and urban tree canopies to help clean and cool the air. The City of Seattle found that although there are variations in tree canopy coverage across the city, there is a statistically significant inverse relationship between tree canopy coverage in Seattle and the percentage of residents who are people of color. A similar significant trend was demonstrated for the percentage of people classified as low-wage earners. For example, the Greater Duwamish area, formerly designated as “definitely declining” and historically dominated by minority groups, has the second lowest tree canopy cover at 15%. Additionally, when assessing vulnerability to heat impacts on a national scale, Seattle has been shown to be on par with Chicago, the site of the 1995 heat-related catastrophe. The health of residents in a given neighborhood is highly correlated with the presence of trees and green space: trees beside roads reduce indoor air pollution in nearby buildings by half, greenery reduces residents’ stress levels, and the closer people live to green space, the less likely they are to be sick. 

Areas like the Greater Duwamish have less tree canopy coverage, which is consistent with historic redlining practices and demographic disparities.


Marlena Skrobe
The majority of Seattle’s urban trees are found in two locations: residential areas (72% of the canopy) and right-of-way (22% of the canopy). This tree-lined street in Washington Park neighborhood overlooking Lake Washington. Washington Park is considered a desirable neighborhood to live in.


The results of this housing and heat study are not quite a smoking-gun demonstration of redlining-induced heat in Seattle as it is in our neighbor, Portland, Oregon. In Portland, neighborhoods designated as “best” are 4.42 °C cooler than average and neighborhoods designated as “hazardous” are 2.67 °C warmer than average. However, the legacy of redlining  highlights that past lending practices have concentrated people of color in areas that are less likely to receive civic investment, which can impact the environmental health of a neighborhood. Seattle is largely unprepared for heat waves that will be intensified by climate change, and certain groups will be disproportionately impacted. Seattle-based climate justice groups like Got Green and Front and Centered are on the front-line of this crisis, planning for the disproportionate impacts of climate change in Washington State and building resilience. We must recognize how the effects of climate change will reinforce the injustices from centuries of racism in the U.S. and center our efforts on equity and the elimination of systems of injustice.


Fat’s Chicken and Waffles restaurant on Martin Luther King Jr Way in Central District. (Info here.)
Marlena Skrobe
The Corner of E Cherry Street and Martin Luther King Jr Way in Central District. Although the Central District was labeled as “hazardous” by HOLC, it fares relatively well in terms of green space coverage. The area, however, faces rapid gentrification and displacement that threatens its once tight-knit community.