Vannessa Mason Evans has lived in Bragtown her entire life. She says she loves the culturally rich, historically Black Durham neighborhood where she has known many of her neighbors since childhood. But it’s always been hot in Bragtown. 

Evans’ monthly utility bill typically ranges from  $200 to $300 in the summer, a common issue in Bragtown, which Evans suspects is due to the neighborhood’s lack of tree canopy. Many homes also lack proper insulation. 

“Some of the landlords don’t care,” says Evans, who serves as chair of the Bragtown Community Association and is descended from enslaved people. “As long as they’re getting their rent, they’re not concerned about that person being in the house getting hot. It may be a person that’s on oxygen … in the squaloring heat, trying to breathe. That makes it worse.” 

Vanessa Mason-Evans

Many Durham neighborhoods experience extreme heat like Bragtown, but high temperatures aren’t distributed equally throughout the county.

If you walked in Haven Hill this June, you likely enjoyed some cool weather, but may not have considered its causes. About three-quarters of this neighborhood’s census tract, Census Tract 16.04, is covered by tree canopy, and barely two percent of surfaces are constructed from impervious materials like concrete, according to the Durham Neighborhood Compass. Late June night-time surface temperatures in this census tract likely range from 55 to 62 degrees. 

If you visited Census Tract 11 in East Durham on the exact same day and time, most streets would feature surface temperatures between 68 and 91 degrees. That’s potentially close to 1.7 times hotter than a neighborhood less than a half-hour away. 

Why do land uses differ so drastically within the same county?  

Haven Hill lies in a census tract that’s over three-quarters white, while the same proportion of residents in Census Tract 11 are people of color, according to the 2019 American Community Survey. 

This stark divide is directly rooted in urban planning. Census Tract 11’s percentage of impervious surface is over 22 times higher than Census Tract 16.04’s, and the predominantly Black census tract’s percentage of tree canopy is about one-fifth the size of its much whiter neighbor. 

Nighttime temperatures above 80 degrees are hot enough to challenge the body’s ability to cool down, according to the 2020 Durham County Community Health Assessment (CHA). Excessive heat, a period of at least two days with temperatures above 90 degrees, is even worse. This means a 91-degree night-time surface temperature poses serious threats. 

Predominantly white neighborhoods contain surface temperatures comparable to the highest measurements in predominantly Black neighborhoods, but they feature a much lower concentration of the county’s hottest surface temperatures at any given time (see maps below). 

The INDY found that residents in Durham’s Blackest neighborhoods are twice as likely to have diabetes, compared to residents in its whitest neighborhoods. They are also three times as likely to lack health insurance, creating a potentially fatal barrier to receiving treatment for heat exhaustion, heatstroke, and aggravated pre-existing conditions.

These disparities aren’t new or unique to Durham, and local government officials and nonprofits have moved to address the problem. Scientists and community volunteers recently participated in the 2021 Raleigh and Durham Urban Heat Island Temperature Mapping Campaign, using sensors to collect data on ambient air temperature, humidity, and GPS location. The Durham County Sustainability Office recommended pursuing this project after analyzing health risks posed by extreme heat. 

But community organizers in hotter neighborhoods say these efforts fall short, and see the heat mapping campaign as a performative effort to make privileged Durhamites feel good about fighting climate change. Local scientists have already provided detailed visualizations of variations in Durham’s surface temperatures, and new satellite-derived data is provided frequently by entities like the United States Geological Survey.

Urban Heat Islands: The science behind temperature variation 

Cities as a whole are typically hotter than surrounding suburbs, says Elizabeth Doran, a professor at the University of Vermont who earned her doctoral degree at Duke University. Doran’s dissertation focused on the relationship between urban form, urban heat islands, and urban systems in the Triangle. 

Urban heat island (UHI) refers to an area where high concentrations of man-made, impervious surfaces increase surface temperatures. Man-made materials absorb heat differently than natural environments, disrupting the sun’s daily process of radiating heat to the Earth—which is then radiated back to the atmosphere.

“They absorb more energy than the natural materials so that exacerbates the amount of heat that gets stored in that local environment, and then changes the way that it’s radiated back to space or the way that it cools off, basically,” Doran says. 

For her dissertation, Doran took a snapshot of the surface temperature in Durham just after 11 p.m. on June 29, 2015. (The INDY used her visualization for this story, since more recent, high-resolution depictions of Durham’s surface temperatures are hard to create without formal scientific training.) The built environment likely hasn’t changed enough since then to significantly alter the distribution of Durham’s heat islands, but their impact has likely been exacerbated by an increase in heat waves, says Doran. 

Surface temperature UHI data can overestimate temperature differences, providing an inaccurate measurement of how humans experience heat. Doran used additional techniques to measure the temperature of the air between roofs and the ground, where people’s bodies directly interact with the heat. She found that this measurement of UHI wasn’t substantially lower than the surface temperature differences observed from space. 

UHI is also exacerbated by the absence of trees—not just the presence of concrete, says Will Wilson, a biology professor at Duke University. 

A large tree draws several hundred gallons of water up through its roots daily while performing photosynthesis. Trees transform this water from a liquid to a gas, which requires heat, Wilson explains.

“It’s just like when you’re boiling water on the stove,” Wilson says. “You have to turn the heat on to get it to boil. You add that heat to evaporate the water that’s on your stove. The same process is going on in the atmosphere in the city. That evaporating water coming out of the leaves of the tree is essentially sucking up heat from the environment and effectively cooling the environment.” 

Although UHI is relatively understudied in smaller cities, it is likely no less of a problem, says Doran, and municipalities will face severe consequences if they ignore it. Heat has already been the number one weather-related cause of death in the U.S. for the past 30 years, and heat-related deaths are rising worldwide. 

The increasing urgency of UHI motivated the engagement aspect of Doran’s dissertation. She encouraged Durham’s policymakers to consider the phenomenon in their urban planning calculus for projects like the now-defunct Durham-Orange Light Rail Transit Project and the consideration of new zoning designations. 

“It didn’t quite get to that level because, and this is often the case with research like this, the people in the planning office, this issue wasn’t even on their radar,” Doran says. “So, it became a matter of educating them that this was potentially an issue that they should care about.” 

The legacy of redlining 

Between 1934 and 1968, eight Durham census tracts were deemed too risky to lend in by the United States’ Home Owners’ Loan Corporation due to the high percentage of Black residents. These tracts encompass more than a dozen neighborhoods, including Hayti, East Durham, Old North Durham, and the Fayetteville Street Commercial District. 

Residents from other Durham census tracts say they have also been—and still are—redlined. When the INDY visited

Merrick Moore residents who expressed these concerns, we saw some large trees on private properties. But residents say this is thanks to their ancestors, many of whom strategically built the houses that stand today to increase shade access. 

In Merrick Moore, many major streets lack not just trees but also sidewalks; people walk on narrow, grassy buffers as traffic zips by. Most communities’ right-of-way includes roads flanked by grassy buffers that feature trees, sidewalks, and pipes—for which governments are responsible. But with the city’s disinvestment, redlined communities were denied adequate infrastructure, including sewers, street lights, sidewalks, and the trees lining them. 

A minor bureaucratic detail ensured that the legacy of these infrastructural choices long outlived redlining’s official demise via the Fair Housing Act of 1968, says Tobin Freid, Sustainability Manager for Durham County and, until 2019, the City of Durham. 

For decades after, the city’s procedure was to only replace trees after they died if a neighborhood requested trees, or if a homeowner was willing to pay part of the cost of a tree in front of their house.

“If there was never a tree there, then they weren’t going to replace it, even until very recently with a very well-meaning Urban Forestry division (UFD),” Freid says. “It was not intentional. It was just these were the procedures that were in place. And so, the city then had to take a really hard look at this and say, ‘Oh my goodness, what are we doing here?’ They had to work with the neighborhoods to plant street trees in places where there historically were none.” 

Black neighborhoods are also home to fewer trees because they contain more apartments and houses with smaller lot sizes, says Wilson, who wrote about Durham’s UHI in his 2011 book Constructed Climates: A Primer on Urban Environments. Apartments also typically feature many parking spaces, increasing the concentration of impervious surfaces in a single lot. Some landlords dislike planting trees since they are more difficult and expensive to maintain than a simple lawn.  

Governments and nonprofits have reached out to formerly redlined neighborhoods, offering to plant trees, and in some cases doing so. Some neighborhoods still don’t have trees because residents don’t want them for many reasons, including not understanding the benefits, not wanting to have to deal with raking leaves or other maintenance, concerns that trees will obscure what is happening on the street, and worries about trees encouraging gentrification. 

Planting trees in Merrick Moore could dominate  the grassy buffers lining the road so that residents will be forced to walk in the street. Further complications could ensue if the city eventually adds sidewalks, as many residents want. Residents also worried the city may not pay to fix damages if nonprofits plant trees whose roots grow and break pipes. 

How governments responded and what we can expect 

These inequities have been on officials’ radars, thanks in part to researchers like Doran. Freid, in particular, has led the charge to address extreme heat, which research determined would impact more people in the Triangle more frequently than any other climate change-related extreme weather. Heat is annual, whereas big storms may come every few years, says Freid. Localized flooding will occur, but Durham lacks large rivers and is too far inland to be severely impacted by sea-level rise. 

Freid collaborated with other local experts to add for the first time a chapter on the health impacts of climate change in Durham’s 2020 CHA—including a section focused purely on extreme heat. Durham is one of a few counties in the Southeastern United States to add such a section to its CHA. 

The CHA analyzed the disproportionate impact that UHI will have on Durham’s redlined census tracts, where structural inequities prevent heat avoidance. Many residents of these neighborhoods lack air conditioning or the means to run it. They are often those who are low-income, currently unhoused, or forced to bear the heat while waiting for public transit, as residents like Evans can confirm. 

“For many of us, we can escape the heat. I have air conditioning in my house,” Freid says. “I have a car, and I can get from my air-conditioned house into my air-conditioned car. It might be inconvenient. It might be hot if I am outside, but I can escape it. But there are a lot of people in Durham who can’t escape it for a lot of different reasons.” 

Planting more trees is one mitigation method that can cool neighborhoods and bring other benefits like flooding control and improving air quality. The city, county, and community partners like Keep Durham Beautiful and Duke University have more than tripled the number of street trees planted each year.  A new non-profit called TreesDurham also plants trees, focused primarily in areas that have historically been underserved. The UFD has established an annual planting goal of 1,500 new trees in city rights of way for every year through 2025. At minimum, 85 percent of these trees are slated to be placed in eight neighborhoods most in need of canopy coverage. The county also allocates $5,000 yearly toward urban trees, says Freid. 

Unfortunately, many UHI mitigation strategies are accessible only to richer communities and others may take a while to bear fruit—like the thinner trees commonly planted by local nonprofits, due to their low cost (often one-hundredth the price of larger trees that provide more immediate shade). 

While residents wait for these trees to grow, gentrification may further concentrate them into Durham’s hottest neighborhoods. As wealth inequality rises, the most marginalized residents will struggle to access health care, keep their air conditioning running, or afford a car. 

Meanwhile, the heat’s frequency will only increase. Durham County is projected to experience around two months’ worth of extreme heat days by 2030, and two-and-a-half months by 2080. 

It’s painful to imagine the toll that this escalating crisis will take on communities like Evans’ where inadequate infrastructure has already made the heat unbearable. 

“I’ve seen people so hot, they’ll be laying down on the ground, with a towel or a jacket, covering their head, waiting for the bus to come,” Evans says. “I’ve seen people sitting on the trashcans near the bus stop, just to have somewhere to sit when they’re standing in the hot sun. I’ve seen spaces where the woods are not close to the bus stop, but people are actually standing back in the woods, waiting for the bus to come.”  

This story has been updated from an earlier version, including to correct the spelling of Tobin Freid’s last name. 

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