In the blog, Tobias James asked a question about a regional breakdown of comics sales — I wanted to copy my post to here to remind me to post the article I'm referring to one day.
As I said there, the Diamond data is aggregated for all of North America. I am sure they could do it internally there, but I have never seen a public version broken out by title.
We used to do reports by store in something called "Market Beat" in Comics & Games Retailer -- a few times I tried to put together regional averages, but found that was just multiplying the workload (and the samples would have been far too uneven over time).
I did do a column called "Blue States, Unread States" in Comics Buyer's Guide #1604 (May 2005), which looked at where shops were and where the most copies per resident were sold of a title that I did have a state-by-state breakout for. I need to get that piece posted online here at some point.
The fewest copies sold per resident were in all the states of the Southeast from Texas to South Carolina, plus Arizona and West Virginia. The largest number of copies per resident were sold in the Pacific Northwest, the Upper Midwest, and New England. The shops-per-capita data was more spread out, although the fewest shops per resident again included the Southeast (this time including North Carolina), plus the Mountain West.
There was a lot more to the piece — including what other factors correlated with where shops were. I am working with the CBG folk to figure the best format for getting the articles online.