THAT left- and right-leaning Americans read different books might be the least surprising fact about publishing. After all, they live in different places, eat different food, listen to different music and, of course, consume different kinds of news. All these reinforce one another; increasingly, progressives and conservatives simply do not know each other. And an analysis of book sales on Amazon, done for The Economist by Valdis Krebs, a data scientist specialising in network analysis and visualisation, bears that out graphically (see chart). People who buy conservative books buy only conservative books, as a rule, and the same is true on the left. Our data is taken from Amazon’s “Customers who bought…also bought…” feature.

Two liberal tomes are dominating the

New York Times

non-fiction bestseller list. In “What Happened” Hillary Clinton admits to some mistakes in her run against Donald Trump, but she spends rather more time on Russian hackers, a herd-like press corps and James Comey, the FBI director whose investigation of her e-mail practices, she thinks, cost her the election. Number two on the

Times

list is “Unbelievable” by Katy Tur, released on September 12th, about her time covering Mr Trump for NBC, a broadcaster. Ms Tur serves up story after story about Mr Trump’s outrageous behaviour towards her, from badgering her about her reporting to kissing her cheek and then bragging about it on camera. He once encouraged a crowd so brazenly to jeer at “little Katy” in the press box that Mr Trump’s own Secret Service detail walked her out for her safety.

But the past year has also seen several thoughtful attempts to break free of the formula of writing for the partisan faithful. One way to do this is to write a sympathetic, or at least fairly researched, look at the other side. Writers from the left in particular have tried this. Arlie Russell Hochschild, a professor emerita in sociology at the University of California, Berkeley, spent months in Louisiana trying to understand how right-wing voters—scraping by economically, their environment devastated by oil and gas companies—nonetheless vote for politicians who promise to slash government services and the Environmental Protection Agency. Ms Hochschild’s result, “Strangers in their Own Land”, published last year, is distinguished—but read mostly by people who read other left-leaning books, not by people like her subjects. The same goes for “White Trash” (June 2016)—a history of the centuries-old forces that shaped an angry white underclass, by another academic, Nancy Isenberg. In today’s tribal environment it is strikingly sympathetic to the block of voters who formed Mr Trump’s electoral base.

Conservative authors, by contrast, seem little interested in analyses of the minds of voters in Brooklyn or Berkeley. It was not always thus. The 1990s and first decade of the 2000s were more fruitful in this regard. David Brooks, a conservative columnist, once perceptively spotted the new confluence of bohemian lifestyles and bourgeois careers and values in his book “Bobos in Paradise” (2000). P.J. O’Rourke, a conservative humourist, perceptively skewered left-wing pieties in books like “Parliament of Whores” (1991). But today, it seems unlikely that Dinesh D’Souza spent much time in honest conversation with Democrats before writing “The Big Lie: Exposing the Nazi Roots of the American Left”, one of the bestselling conservative political books of the past year.

Braver writers on the right have taken another approach: critically examining their own side. Two Republican senators have written books filled with alarm at the rise of Mr Trump. Ben Sasse, from Nebraska, never endorsed his party’s nominee. In “The Vanishing American Adult” he talks about a country now in “perpetual adolescence”, and stresses family, reading and community service in a culture he sees as giving way to selfishness, celebrity and screen-time. It is the rarest of things, a book by a politician being read by both tribes.

A more explicitly political book by a conservative on conservatism has not shared that success. Jeff Flake, an Arizonan senator, fears that his party has made a bad deal for power, by standing squarely with Mr Trump in exchange for giving up their firm support for free trade, limited government and American leadership of the democratic world. His “Conscience of a Conservative” was meant as a cri de coeur to his fellow Republicans. Those who bought it on Amazon, though, were more likely to buy “How The Right Lost Its Mind” by Charles Sykes, “The Conscience of a Liberal” by Paul Krugman, or even Ms Tur’s “Unbelievable” than any book by another prominent conservative writer.

Writers on the left have not shied away from “blue-on-blue” criticism of their own side. In “The Once and Future Liberal” Mark Lilla of Columbia University has criticised “a kind of moral panic about racial, gender and sexual identity that has distorted liberalism’s message and prevented it from becoming a unifying force”. Republicans, it might seem, should snap up a book arguing that the left has gone overboard in focusing on members of minority groups at the expense of “ordinary people” in middle America. But Mr Lilla’s book is being read overwhelmingly by those who read other liberal books.

One of the most favourably reviewed books was also a surprise bestseller: J.D. Vance’s “Hillbilly Elegy”. Mr Vance’s family, who “would rather shoot you than argue with you”, left Appalachian Kentucky for a steel town in Ohio. They are the “white trash” that other books have focused on, too, aiming to work out how they abandoned the Democratic Party. But Mr Vance is an insider, not an anthropologist. Drugs, drink and violence plagued his family and his town, and Mr Vance, a political conservative, is critical of this culture. Highbrow Democrats and Republicans alike have admired his book, published in June 2016, but it is mostly bought by Democratic-leaning readers.

Perhaps the most mournful category of crossover book is the story of the hapless Clinton campaign. One book, “Shattered: Inside Hillary Clinton’s Doomed Campaign”, is an account of Ms Clinton’s staff and messaging turmoil by two veteran journalists, Jonathan Allen and Amie Parnes. Politicos of all stripes seem to be interested in the story. Not so with “The Destruction of Hillary Clinton”, by a feminist professor at the University of Kentucky, Susan Bordo. She argues that America was simply not ready for such a strong woman. Most of its reviewers on Amazon seemed to agree, giving it five stars. Nearly all of those who disagreed did so violently, giving it one star; perhaps they bought the book mistakenly believing that the “destruction” of Ms Clinton promised in the title would be narrated with glee.

Jeff Bezos, Amazon’s founder, has bought the Washington Post, and urged upon it the motto: “Democracy Dies in Darkness”. But Amazon conquered the book market in part on the strength of its “recommendation engine”. That now contributes to the dark spots in Americans’ knowledge of their political opposites. Whether Amazon will—or even can—do anything to change that is yet to be seen.