Goodreads collects data from their users to map it: 

On the map above, the readers in the red states rated the book highly (the darker the red, the higher the rating), while readers in the blue states gave it a lower rating). The Midwest and the South represent The Twilight Belt, while the coasts were decidedly less impressed with the book. Reviews were mostly distributed according to population, with the notable exception of Utah. Utah is the 34th most populous state in the US, but it generates the 6th most reviews of Twilight. In terms of cities, Salt Lake City—the 125th largest city in the country—is second only to New York in number of Twilight reviews.