By Reid J. Epstein and Deepa Seetharaman
Mark Zuckerberg is trying to understand America, so he's embarked on a journey to meet people like hockey moms and steelworkers who don't typically cross his path.
But there are rules to abide by if you are an ordinary person about to meet an extraordinary entrepreneur.
Rule One: You probably won't know Mr. Zuckerberg is coming.
Rule Two: If you do know he's coming, keep it to yourself.
Rule Three: Be careful what you reveal about the meeting.
While the Facebook CEO has built a social network that inspired people around the world to share the most intimate details about their personal lives, his team goes to extraordinary lengths to keep his movements under wraps and control how he is perceived. Midway through a "personal challenge" to travel to 30 states he'd never visited, the 33-year old aims "to talk to more people about how they're living, working and thinking about the future," he wrote in January on his Facebook page.
Among those people was Kyle McKasson, manager of the Wilton Candy Kitchen, a century-old shop on the town square in Wilton, Iowa.
He was at work one Monday afternoon in June when two men and a woman dressed in jeans and button-down shirts entered the store, which is a regular stop on Iowa's presidential campaign circuit.
The three said they were from California on a business trip on their way to Chicago and asked Mr. McKasson for a tour of the store and its museum of the history of Wilton, population 2,800. They didn't tell their names, he said, and he thought it impolite to ask.
Four days later, the same three people returned to the candy store, and one of his new customers revealed their true mission: "Mark Zuckerberg will be here in five minutes."
A startled Mr. McKasson, 54, asked: "What do I need to do?" he recalled, and was told: "Nothing."
Mr. Zuckerberg walked through the red-and-white store door. He ordered a $5.75 chocolate malt. An assistant paid the world's fifth-richest man's tab with a debit card.
The tech titan chatted with the young cashier about her future plans and spoke to Mr. McKasson about life in Wilton and the city's downtown revitalization efforts.
Members of Mr. Zuckerberg's team plan his visits with secrecy, but there are rare instances of the Facebook CEO's cover being blown. The result: chaos.
When someone let slip he'd be at the Kusanya Café on Chicago's South Side, Renée Banks, a barista, said she had to fetch extra chairs for the 100 people who showed up.
Amy Dudley, a spokeswoman for the Chan Zuckerberg Initiative LLC, an entity formed in 2015 by Mr. Zuckerberg and his wife, Priscilla Chan, which is helping to arrange the CEO's tour, said the design of "these visits is to have the most honest and candid interactions and discussions as possible, without the additional attention that's likely to come as a result of word getting out ahead of time."
For nearly a decade, Mr. Zuckerberg has started every year with a "personal challenge." In 2009, this meant wearing a tie every day. Another year, he swore only to eat meat that he had personally slaughtered. "I just killed a pig and a goat," he boasted in a private Facebook post in 2011.
Facebook, the 13-year-old company he co-founded, now has two billion monthly active users. Its market value is $446 billion.
In Wilton, Mr. Zuckerberg's advance team had stopped at city hall to secure a meeting with Wilton Mayor Bob Barrett and City Administrator Chris Ball to discuss life in rural Iowa before the CEO went to the candy store.
But Messers. Ball and Barrett were asked not to tell anyone Mr. Zuckerberg was coming. Mr. Ball said Mr. Zuckerberg's representatives instructed them not to relay verbatim quotes from their discussions with him if asked by reporters.
"They asked me not to quote what Mr. Zuckerberg said," Mr. Ball said. "They said to refer people to their press guys."
Mr. Zuckerberg spent the July 4 weekend in Alaska, the 15th state he's visited on his tour since it began in January. He stayed at the Kachemak Bay Wilderness Lodge, a $1,000-per-night fishing resort on the Kenai Peninsula. A receptionist said the lodge's owners wouldn't discuss the visit. "You have to call Amy Dudley," she said.
Ms. Dudley, a former aide to Vice President Joe Biden and Virginia Sen. Tim Kaine, said Mr. Zuckerberg declined to be interviewed for this article.
Despite his world-wide fame, Mr. Zuckerberg isn't always recognized by his surprise hosts.
In June, he attended an Iftar dinner in Minneapolis. Mr. Zuckerberg arrived after the prayers and the other people in the room, who were mostly refugees from Somalia, didn't know who he was, said attendee Mohammed Jama.
Blues musician James "Super Chikan" Johnson was booked in February to play a concert funded by a mystery client at the Ground Zero Blues Club in Clarksdale, Miss. Mr. Johnson, 66, said it is unusual for him to not be told for whom he'd be performing. When he was on stage setting up his equipment, Mr. Zuckerberg approached.
"They said, 'That's Mark Zuckerberg.' I said, 'Who dat?'" Mr. Johnson said. "They said, 'It's the Facebook guy, the guy who owns the Facebook. I said, 'You've got to be kidding me.' I had no idea who he was."
The secrecy surrounding Mr. Zuckerberg's visits has nearly led to his target audience blowing him off.
Adam Kragthorpe, who runs a local youth hockey program in Minnetonka, Minn., deleted the initial email from James Eby requesting a meeting for "a Fortune 500 CEO who is traveling the United States and visiting a wide range of communities."
"We thought it was a multilevel marketing scheme," Mr. Kragthorpe said.
Mr. Eby, who planned travels for four Defense secretaries in the Obama administration, is now a contractor working for the Chan Zuckerberg Initiative. He declined to comment.
Two days after he emailed Mr. Kragthorpe, Mr. Eby arrived unannounced at the hockey rink.
Mr. Kragthorpe said he was told that Mr. Zuckerberg would like to visit with hockey families a couple of days later. He said Mr. Eby told him not to tell anyone the Facebook CEO was coming and asked that people at the rink not photograph the CEO.
The Zuckerberg entourage, which can be up to eight people, includes a professional photographer. His aides said there is no prohibition against others snapping pictures.
In Newton Falls, Ohio, Dan Moore got a call in April from Jimmy Dahman, a former presidential campaign field organizer for Hillary Clinton in Ohio. Mr. Dahman doesn't work for Mr. Zuckerberg's organization, but was acting as a volunteer, he said.
He wanted to know if Mr. Moore, a Democratic union steelworker who was a volunteer for Donald Trump's presidential campaign, would host "a billionaire philanthropist from California" at his home five days later.
Four days later, Mr. Moore, 57, was standing in his driveway waiting for his mystery guest. Fifteen minutes before a pair of black SUVs arrived, he was told he'd be joined by Mr. Zuckerberg.
Mr. Moore and his family enjoyed a dinner of chicken Francaise and baked whitefish Mr. Zuckerberg's staff had catered from a nearby restaurant. As Mr. Zuckerberg was leaving, he made one request, Mr. Moore said.
"He said, 'If there are any news reporters that call you, just make sure you tell them I'm not running for president.'
Write to Reid J. Epstein at email@example.com and Deepa Seetharaman at Deepa.Seetharaman@wsj.com