President Obama and Mitt Romney may be neck-and-neck in the latest nationwide polls, but if America picked presidents based on summer reading lists instead of fall voting, this election wouldn't even be close.

At least that's the impression given by Amazon's new Election Heat Map, which uses sales data from overtly political books to create a color-coded map of U.S. literary leanings. It's updated daily, and thus subject to change before November, but for now it shows a nation of conservative bookworms who don't think much of Obama.

A whopping 44 states are currently shaded Republican red on Amazon's map, and not just GOP mainstays like Texas and Mississippi. Every swing state and even many liberal bulwarks have a scarlet hue, including California, Colorado, Illinois, Hawaii and Wisconsin. Aside from the District of Columbia, only four states are shaded Democratic blue: Massachusetts, New York, Rhode Island and Vermont. As of this writing, Maryland and Minnesota are the only two neutral-colored states.

Many Amazon customers must still live in those blue and neutral enclaves, though, since the national data are slighly less lopsided. While 88 percent of states bought more "red" than "blue" books in the past 30 days — and just 8 percent of states did the opposite — Americans' overall purchases were 56 percent red and 44 percent blue. Nationwide, Amazon's top-selling red book was Edward Klein's "The Amateur," and the No. 1 blue book was "The New New Deal" by Michael Grunwald.

Of course, as Amazon points out, this map isn't scientific and may tell us nothing about the actual election. "Books aren't votes," the e-retailer says in a statement, "and a map of book purchases can reflect curiosity as much as commitment." While there's a one-ballot limit per registered voter, for instance, a single book club may buy dozens of books each month on Amazon, and some politically active readers might not be counted because they shop at brick-and-mortar stores or other websites.

And although the publishing industry was once known for leaning left, it has begun embracing more conservative booksellers like Regnery, Eagle, Threshold Editions, Crown Forum and Broadside Books — as reported in 2008 by policy magazine City Journal and more recently on "The Daily Show." Yet despite such caveats, Amazon adds that "we hope our 2012 Election Heat Map will provide one way to follow the changing political conversation across the country during this election season."

If you're wondering how Amazon classifies books as either Republican or Democratic, the company offers this explanation on its website:

"We take the top-selling political books on and categorize them as 'red,' 'blue,' or neutral. We classify books as red or blue if they have a political leaning made evident in book promotion material and/or customer classification, such as tags."

As for how it then translates that into a heat map:

"We compute percentages, updated daily, for each state and the U.S. by comparing the 250 best-selling blue books during the time period against the 250 best-selling red books during the same time period, including new book launches. If the same book title has multiple formats (paperback, Kindle books and Audible Audio), each format has a separate sales calculation. The list only includes paid, not free Kindle books. All orders during the period are given equal weighting in the calculation. States with higher percentages of red or blue purchases are colored more darkly, and states with an even 50-50 split are colored neutral."

Book sales are little more than a "novel" way to think about election-year politics, as Amazon cheekily puts it, especially when you only use one retailer's data. But they can still offer an interesting look at fluid political attitudes in the U.S., as well as publishing trends in the e-reader era. They also add another layer to the ongoing study of America's political psychology, along with details such as conservatives' relative distrust of science, liberals' tolerance for unpleasant images, and the support of yoga teachers and insurance agents for Obama and Romney, respectively.

And since both major parties' presidential and vice presidential candidates are published authors themselves, Amazon's sales stats also give us intriguing head-to-head comparisons 10 weeks before the election. Obama has a substantial lead over Romney, for example, with "The Audacity of Hope" outselling "No Apology" 63 percent to 37 percent. But that margin is more than eclipsed in the VP matchup, where "Young Guns" (which Paul Ryan co-wrote with House Majority Leader Eric Cantor) is crushing Joe Biden's "Promises to Keep" 95 percent to 5 percent.

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Russell McLendon ( @russmclendon ) writes about humans and other wildlife.

Amazon offers 'novel' look at U.S. politics
The online retailer's new 'Election Heat Map' uses book-sales data to reveal a widespread Republican streak among its American customers.