To create this map, I derived the average color of each state flag and assigned it to its respective state. Only the obverse side of each flag was used. The notion of average color depends on the color space used; for the purpose of this map, I used a Lab color space (CIELab D50). The background is set to the average color of the USA national flag.

It’s interesting to see that bluer averages tend to be associated with northern states. Redder hues (including purples and pinks) are more southern, and particularly focused in the southeast. The states that chose not to conform to red, white, and blue also stand out (e.g., Washington, New Mexico, Maryland, New Jersey).

Data source: http://flaglane.com/category/american/