According to Amazon which tallied all book, magazine and newspaper sales in both print and Kindle format since January 1, 2011, on a per capita basis in cities with more than 100,000 residents.
Not only did they compile data on book sales per city, but they took note of what kind of reading was done by buyers in those cities.
Cambridge is number one and selects a lot of non fiction. Duh. Harvard.
Alexandria Virginia is number 2 and gets a lot of children's books.
Boulder Colorado is into cooking, food and wine.
I'd like to see what is most popular for the other cities, St. Louis is Number 20.
The entire list can be seen here.