Baseball's Borders

This visualization of Major League Baseball's borders (in terms of which team is "the team" for different geographic areas) has been circulating online. I like its depiction of baseball rivalries.

The first thing I noticed is how much more area the Giants occupy than the Dodgers. However, I really want to see how the visualizations looks when one uses a cartogram to normalize based on population size.

(Tip of the cap to Tom Maccarone [who sent it to me most recently], Jennifer Victor, and others.)