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A map of MLB geography, by proximity

(Map courtesy Nick Bonard)

Baseball maps have been much in the news this month, after the publication of that map showing the most popular MLB team by Facebook likes. Here’s another baseball map, with a much different way of dividing the country.

Nick Bonard, a northern Virginia native who got a Masters in urban planning from Harvard, divided the country into baseball territories based on the closest MLB stadium, as the crow flies.

This obviously has nothing to do with actual baseball loyalties. North Carolina is not Nats territory, even if large parts of the state are closer to Nats Park than to Atlanta, and the A’s don’t dominate northern California by virtue of being slightly east of San Francisco. And the more diffuse Western and Southern cities, of course, have much larger territories than the packed Northeast.

Still, I’d advise you take a quick glance at the chart on the bottom. If you assign population to these territories based on the 2010 census, you’ll find Washington comes in third. That means only two teams boast more people who live closer to their city than to any other MLB park: the Braves and the Astros. Kind of interesting.

Baltimore, on the other hand, finishes near the bottom in this measure, being hemmed in by Philadelphia, Washington and Pittsburgh.

Read more on Nick’s blog. He also has a version focused just on the Mid-Atlantic region, to show you the dividing line between the Washington and Baltimore territories.

UPDATE: This map has been updated, after some readers pointed out a few minor problems, mostly with the western borders. Via Nick:

The original boundary lines were produced by running a computer program within a geographic information system software that generates “Thiessen Polygons.” Without this program, it is extremely time consuming to draw the polygons by hand – especially for a side project. The mistake I made was assuming that the polygons drawn by the computer were correct, and not double checking by hand. For this revision you see above, I calculated the Thiessen polygons myself using this process (in PDF). I’ve checked and rechecked the distances this time, and I’d say the accuracy is +/- 1,000 meters.  I’ve also updated the population figures. I had some good comments wondering if the the original errors were due to the the projection.  Just FYI – I used a Albers equal-area conic projection, which preserves polygon areas but has some minimal shape/straight line distortion.  As always let me know if you have questions.