Redlining’s Legacy in Heat Inequality: Exploratory Page

Jason Kao

April 26, 2021

In the following map, explore how summertime temperatures affect neighborhoods of different HOLC grades in various cities and decades. When you scroll into the map, a layers interface appears. You can toggle HOLC boundaries. You can also toggle the visibility of impervious surfaces, as well as the visibility of two categories of imperviousness.

When any impervious surface is visible, the color legend becomes a bivariate matrix of colors. Clicking on any square in the legend filters the map to show only HOLC areas with that color.

The final research document is available here.

The temperature distribution in by HOLC grade is visualized in the density plot below.

After running Tukey’s Test at a 95% confidence interval for , we can observe in both years which HOLC grades’ neighborhoods were significantly cooler or hotter than neighborhoods in other grades.

Go back up to view the map.


Nationwide, the distribution of temperatures for each HOLC grade shows that formerly redlined neighborhoods experience hotter summers, both in 2000 and 2020. Applying Tukey’s Honestly Significant Differences Test at a 95% confidence interval gets us the results below.

The individual per-polygon temperature means are shown in the following density plot.