Let's get this out of the way real quick: these are not the #1 artists in these states, and those colors refer to population densities. These are the most distinctive popular artists in their state (bands that certain states like and other states can't stand), according to Paul Lamere of MusicMachinery.com. If it were the most popular artists, this would be one map which would read "Either Beyonce, Drake, Toby Keith or Lorde depending on what Clear Channel wants today."
There have been a lot of great US maps recently, including the best movies set in each state, what each state's reputation is on Google, and finally a straight-up, best-to-worst ranking. That being said, people get worked up over favorite movies and clichés, but fights about music can lead to friendships ending in the blink of an eye. I hope this map doesn't lead to civil war.
So, "distinctiveness" is measured by looking at the top 100 artists in each state, and then seeing which of those lands furthest down the charts in other regions. Additionally, states could not have the same distinctive artist—artists were assigned to states in order of population. So, "Bonobo" may be distinctive in other weird liberal states, but California got it first, so Vermont will have to settle for Phish (as they have for 20-odd years).
Also, I'm not sure exactly how he chose which regions to compare, but this is not one state compared to 50. Southern states get compared to Northeastern states, etc. This is why Hillsong United, a super-Christian band, is South Carolina's chosen band and James Blake, an English EDM artist, is New York's. No one is saying that those are their favorite bands.
To do this, Lamere built an app, "Regionalism in U.S. Listening Preferences", that compares Spotify habits across states, regions, and compared to the whole country. For example, here's a quick look at how the top 200 artists in Arizona are different from the whole US:
Dear Arizona, please join us in the current decade (and not just with music). (via)
While most people in your state listen to the same terrible Clear Channel options that are being blasted into every store, club, car, elevator or whatever in America, it's interesting to see those rare things that we do differently. In other words, it's interesting to see what your state considers pretty OK and everyone else considers screeching, obnoxious, disgusting garbage. Or, when it comes to New Jersey and Bruce Springsteen, what your state loves and no one else really gets the obsession. I mean, everyone loves Bruce, but Jersey's the only state with a weird shrine in the closet covered in locks of hair.
(by Johnny McNulty)