NC Court-Ordered Redistricting 2019

Pursuant to the gerrymandering case Common Cause v. Lewis, North Carolina's state-legislative electoral districts had to be redrawn due to partisan bias. The districts also had to be redrawn between 2016 and 2018 due to racial bias, which was handled by the case North Carolina v. Covington, but that transition isn't detailed on this map.

Colors

Each district (for example, house 11, senate 32, or house 103) has a color, and it keeps that color whether the current displayed map is the one that was used for the 2018 midterm elections or the new one which will ostensibly apply for the 2020 elections. Since the changes to the shapes of districts from the 2018 maps to the 2020 ones are small, this makes it easy to see how a district has changed.

Five different colors are used, each at a different level of overall brightness. This is intended to ensure that the different colors are distinguishable even to viewers with a form of color vision deficiency.

Normally, four colors would suffice, but the four-color theorem does not apply in this case, because the change over time adds another dimension that districts can use to find and touch one another. In particular, house districts 70 through 74 are all connected to each other, in one year or the other (or both), which forces the use of a fifth color.

Despite the use of shades of red and blue, the color of a given district doesn't really mean anything.

Buttons and their Labels

The labels of the two toggle buttons (year and layer) indicate the current state of the variable that that button controls.

Long Map Loading Times

A map layer won't actually load until it's about to be displayed, and all four layers are transmitted as compressed KMZs rather than uncompressed KML in order to conform to the filesize limits of the KmlLayer object class that puts them on the map. As such, there really is no fix for that.

Sources