As a result of flat shading all of the polygon's vertices are colored with one color, allowing differentiation between adjacent polygons.
There are two versions of this family, the first is colored with one dominant color and a black background and the newer version is much more lighter in shade, replacing the black background with a second dominant color similar in shade to the first one.
Coloring an area with one color is not meant to imply that the TRI amounts are uniformly distributed throughout that area; instead it should be interpreted as a color representing, for example, the total amounts reported by facilities in that area.