Back in 2000, Kathy L. Patrick opened a shop in East Texas called Beauty and the Book, with hopes of creating a place where people could gather around her two passions: beauty and books. There were paperbacks and hardcovers on the shelves and hairdressers ready to do your wash and curl.

Soon after that, Patrick founded the shop’s book club, which she called The Pulpwood Queens of East Texas. It began with six strangers and is now one of the largest book clubs in the world, with over 350 chapters nationwide and in eleven countries. The club meets once a month and includes both men and women (the men are referred to as The Timber Guys) who range in age from early twenties to nearly ninety years old.

Needless to say, when Patrick’s group picks a book, it means a significant sales boost for that book. And The Pulpwood Queens of East Texas is but one part of a phenomenon that has become, according to some, the lifeblood of the book business. Book clubs can singlehandedly catapult a book from obscurity to thousands of readers, using the age-old meritocracy of word of mouth. Book clubs have kept books like Jeannette Walls’ Glass Castles and Elizabeth Gilbert’s Eat Pray Love, on bestseller lists for years.

The Encyclopedia of Community: From the Village to the Virtual World, notes that in 2003, a Google search for “book club” returned 424,000 hits; now it returns 40 million. In the past fifteen years, book clubs in the U.S. have become commonplace, if not ubiquitous. They are cultivated by celebrities, bookstores, libraries, community centers, municipalities, and of course the occasional beauty shop. According to Harvey Daniels’ Literature Circles: Voice and Choice in Book Clubs & Reading Groups, in 1990 there were about 50,000 book clubs in the U.S. By 2000, the number had almost doubled— low estimates count at least 100,000 book clubs. The sales power of these clubs are hard to measure, but the most conservative estimates point to some incredible numbers. If one assumes each club has ten members, and picks six books a year, that’s 60 books sold per club, and with 100,000 clubs in existence, that’s 60 million books. And that’s not even counting Oprah.

Oprah Winfrey started her book club in 1995 and now has about 2 million members. Every time she picks a new book to read, the book’s sales skyrocket. In 2003 she chose John Steinbeck’s East of Eden and it sold 60,000 copies in one hour. When she selected Leo Tolstoy’s Anna Karenina in 2004 it sold 79,000 copies in one week—doubling the book’s total U.S. sales since its English publication in 1886.

The first known “literature circle” in America was founded in 1634 by a Puritan settler, Anna Hutchinson, as a women’s Bible study circle. Though Hutchinson’s group was eventually banned in Boston by suspicious Puritan males, group discussions, usually religiously based, continued. In 1840, Margaret Fuller founded the first bookstore-sponsored club in Boston and by the mid-1800’s, book clubs were spreading throughout the Midwest both as social events and intellectual opportunities. In 1926, Harry Scherman founded the Book-of-the-Month-Club and in 1927 the Literary Guild was founded, both of which distributed book selections to thousands of members by mail.

The 2009 the National Endowment for the Arts (NEA) survey Reading on the Rise reported that for the first time since 1982, the number of U.S. adults reading literary material had risen from 46.7 percent in 2002 to 50.2 percent in 2008. In all, 16.6 million more adults are reading today than at the beginning of the decade. Of course this isn’t only the result of book club popularity (literacy rates have increased, education rates have grown, book production is rising) but book clubs have popularized—and socialized—literary reading.

“I think the reason our book club has grown to be so large is we make reading fun,” says Patrick. “We don’t take ourselves very seriously. I mean, it’s perfectly okay to wear big hair, tiaras, feather boas and leopard accessories. Girls love it no matter the age and now the men have come on board too.”

Many online clubs, like The Progressive Book Club and Women of Faith, cater to specific demographics while other clubs, like those of independent bookstores, provide members with special editions. Square Books in Oxford, Mississippi has a Signed First Editions club that ships out one signed book per month to the nationwide club at list price. Powell’s Bookstore in Portland, Oregon hosts the Indiespensible Program through which members receive signed first editions from independent publishers in limited edition packaging with bonuses like hand-wrapped truffles or playing cards.

Some colleges have traditionally given their incoming freshman a book they hope they’ll read before arriving on campus. These “common read” or “freshman read” or “all-campus” read programs have grown exponentially in popularity over the past ten years. Indeed, it’s increasingly rare to find a college that doesn’t have such a program. When a larger university, like Michigan State or the University of Arizona, picks a book, it can mean sales of 10,000 or more copies of a given book—far more than many books sell in their lifetime. These copies are bought by the university at a discount and everyone—readers, campuses, publishers and authors—can benefit. The thousands of students go on to tell thousands more about the book, and word-of-mouth continues.

In 2005, the NEA initiated multiple reading incentive programs that function as large-scale reading clubs. The Big Read now involves nearly 500 communities across the country and sponsors literary discussion groups and panels. One City, One Book, a program that encourages entire municipalities to read the same book, has developed chapters in every state since its 1998 inception in Seattle. There are thousands of such programs, bringing together the smallest towns and, in some cases (like South Dakota, for one) whole states.

The clubs are, at their roots, stimulants for a healthy book business, but their popularity is also indicative of a growing class of readers. Book club members are reliable book buyers not because they have to, but because they choose to buy a new book each month. As Oprah’s Book Club has done countless times for writers and publishers, book clubs invigorate a healthy book culture on both sides of the press. Not only are people still reading, they’re still buying, and in many cases, a book club is the only excuse they need.

“I am way too busy,” says Patrick. “Book club is the one time of the month I can take the time to be with my friends, share a meal, perhaps a glass of wine, talk about the author and book with the author—kind of like playing hooky from life for an evening. It’s a legitimate way to be with your friends… And it’s all about sharing our lives and community.”