Michelle Obama made history in 2009 when she became the first African-American first lady of the United States.Now she’s breaking ground again with an unprecedented book tour, selling out 20,000-seat stadiums in 10 cities across the United States. Never before has an author appeared to promote a book before audiences anywhere near that size.The 54-year-old Obama has mostly stayed out of the spotlight since she and her family left the White House in January 2017, but she’s back in its glare. Becoming, her new memoir, was published by Crown on Tuesday, and her media appearances are underway pretty much everyplace but Fox News (including an interview on 2 Dope Queens that its hosts, Phoebe Robinson and Jessica Williams, announced would be their final podcast).In interviews, Obama is discussing personal details she writes about in the book, like the problems with infertility that she and Barack Obama faced and her anger at the baseless “birther” rumors about her husband peddled by Donald Trump, which she felt endangered her family.That level of media attention is typical for a memoir by a former first lady or president (and most of them have written such books). What’s utterly new is that book tour.Even for bestselling major authors, an in-person talk and book signing is likely to draw dozens or hundreds of fans, not thousands. Most book tour stops have free admission or modestly priced tickets. Last year, Hillary Rodham Clinton toured with her memoir about the 2016 campaign, What Happened? Sellout crowds paid as much as $3,000 for VIP packages, but most tickets were much less, and Clinton appeared in venues that seated around 2,000.Ticket prices for Obama’s tour range from a limited number at $29 in some venues to around $3,000 for VIP packages, with most seats priced at several hundred dollars. Live Nation, which usually produces tours for the likes of Beyoncé and U2, is shepherding Obama’s tour, booking her into venues that seat from 14,000 to 23,000, like the American Airlines Center in Dallas, the Barclays Center in Brooklyn and the Capital One Arena in Washington, D.C. (Obama and Live Nation have announced that 10 percent of ticket sales will be donated to a variety of charities, and that 10 percent of tickets will be given away to schools and community organizations at each stop. Obama is also donating a portion of all proceeds from her book to her Global Girls Alliance.)The tour kicked off Tuesday in Obama’s hometown of Chicago. Before her sold-out appearance at the United Center, home of the Bulls and Blackhawks, Obama made an official first stop in the afternoon at an independent book store, the Seminary Co-op in Hyde Park. (The Obamas lived nearby before moving to the White House.) There, 500 admission wristbands were snapped up last Sunday, and those hundreds stood in a line around the block on a chilly Tuesday afternoon to meet her.The United Center show was hosted by another Chicago superstar, Oprah Winfrey, who interviewed the author. One of Obama’s revelations was about an event she told Winfrey she forgot to put in the book: her emotional response to departing from the White House after Trump’s inauguration. “When I got on the plane, I think I sobbed for 30 minutes,” she said. “I think it was just the release of eight years of trying to do everything perfectly. I said to Barack, ‘That was so hard, what we just did; that was so hard.’ ”On the rest of her tour stops, the former first lady’s interviewers are an array of other high-profile women: inaugural poet Elizabeth Alexander, presidential adviser Valerie Jarrett, journalist Michele Norris, comedian Phoebe Robinson and actors Sarah Jessica Parker, Tracee Ellis Ross and Reese Witherspoon. Obama will also appear in smaller venues in Paris and London.The rock star book tour is just one indication of interest in Becoming. The global first printing was 3 million copies, published in 31 languages.On Monday, Becoming was ranked No. 1 in all book sales on Amazon, and Barnes & Noble announced that it had racked up more preorders than any other adult book since Harper Lee’s Go Set a Watchman was published in 2015. In St. Petersburg, Tombolo Books owner Alsace Walentine said preorders for Becoming were brisk enough to make her order extra copies of it for her popup bookstore at the Times Festival of Reading on Saturday.Just for good measure, on Monday Oprah announced Becoming was her next book club pick.It sounds as if Crown Publishing (a division of Penguin Random House) will be pleased with these first results of its 2017 deal for separate memoirs by Barack and Michelle Obama. No official figures were released, but the Financial Times reported that the couple signed for $65 million. Barack Obama, of course, has a history of writing bestselling memoirs, but Becoming is Michelle’s first one.It’s certainly making a splash. Are we likely ever to see a book tour of this magnitude again? Sure: No title or publication date yet, but Barack Obama’s memoir is due next year.Information from Times wires was used in this report. Contact Colette Bancroft at [email protected] or (727) 893-8435. Follow @colettemb.