Are Montreal, Toronto, and Los Angeles the agenda-setters for alternative music in North America, with Atlanta setting the tone for hip-hop? Such, at least, are the tentative findings of a study that uses network theory to study the "geographic flow" of music.

The researchers drew on data from Last.fm, which, in addition to being a streaming service, lets users upload information about all music played on their devices ("scrobbling" is the term of art). Researchers drew on 153 weeks of such information, covering 200 cities...