Sadly, it turns out this heartwarming story is little more than an urban myth. Jessica Amanda Salmonson retires it here:
'This notion originated initially with the Book of the Month Club advertising department. In 1991, the 2,000 forms labeled "Survey of Lifetime Reading Habits" were sent to Book of the Month Club readers in a bizarre scam that hornswoggled the Library of Congress in promoting the Book Club. The Library of Congress fit it into their reading promotion project but this was a survey of nothing but the effectiveness of Book of the Month Club's advertising. Thus the top ten books included similar offerings from the Book Club come-on-attractions leaflet, Betty Friedan's The Feminine Mystique, Scott Peck's The Road Less Travelled, & Gail Sheedy's Passages. Truly a list of immortal classics.
A study or a credible survey with any degree of applicability would have required statistical controls & other factors to ensure some degree of scientific validity & would not have been restricted to book club customers selected by the book club. But inasmuch as this was just a promo & not legitimate research on reading in America, the only "statistical finding" required was the finding of good advertisement copy.
This Book of the Month Club promotion mailed out in cooperation with the Library of Congress reading promotion program not surprisingly established that Book of the Month Club titles were very significant to Book Club customers, most especially the few titles listed on the introductory offer form. Among which Ayn Rand's Atlas Shrugged placed #2, after the Bible.
So this "finding" applied to 1991 Book of the Month Club readers, but somehow in the wake of this phony study it was transmuted into Rand having written the most important book to all Americans for all time. That now decade-plus old ad campaign still gets paraphrased by Randians as "recent" & as "a study" when it is (or was) neither, claiming always that it was conducted by the Library of Congress, since even Randians know that citing ad copy composed by the Book Club sounds just as cheezy as it is.
A bit more recently (in 1999), advertising hacks hired by television producers began promoting a made-for-TV Ayn Rand docudrama, plus a cable documentary, & associated book tie-ins & videos. Being it would seem a cut-rate outfit, they just found the old Book of the Month Club blurbs, paraphrased this so closely that the Book Club ad writers should have sued them as plagiarists, then did a massive press release campaign which repopularized the 1991 Book of the Month Club ad scam in context of how important it is for everyone to watch TV.
That 1999 publicity packet was afterward copied onto the back covers of new editions of Rand, trying to take advantage of the television exposure, so that by now it is "common knowledge" that the Library of Congress proved something it never proved with a study it never conducted..." - Jessica Ann Salmon, (via Mike Huben's "Critiques of Libertarianism" site)