After
You see two maps. The first one is the "before" picture, the other is the "after" picture. There are seven distinct colour codes.
The colouring is based on data provided by a US-based company. (There are more than seven categories in the data, but in the map above, some of the lower ones have been collapsed into one group for ease of representation.)
This company has been issuing this data since 1916. A recent change to this data, which gives rise to these "before" and "after" maps (there is only difference between them), caused much hullabaloo. What change?
Images: Wikipedia
