LANSING, Mich. — Sure, you could wear a campaign button. But a photo with the candidate is so much more versatile: suitable for avatars, posting with a clever hashtag, even printing out and framing if you want to go analog.

Posing for the camera with a presidential candidate used to be a perk generally reserved for wealthy donors. At Senator Elizabeth Warren’s events, all it costs is passing some time in a well-organized selfie* line.

*The pictures are not technically selfies.

At a recent event in Lansing, a small army of campaign staff members — working like a factory assembly line that hums along — helped usher voters through their encounter with Ms. Warren in eight key steps.

Each staff member plays a different role.

Since entering the presidential race, Ms. Warren has taken pictures with more than 38,000 people, her campaign estimates. Ms. Warren says the photos are part of her effort to build what she likes to call a “grass-roots movement.”

“It’s how I make this real, person to person,” she said in an interview. “I know I won’t be able to shake the hand of every single person; I know I won’t be able to take a selfie with every single human being in this country. But I’m going to try.”

Other Democratic candidates also take pictures with voters, even if they lack the well-orchestrated selfie line that Ms. Warren employs. Senator Bernie Sanders recently started forming a selfie line at his events. Mayor Pete Buttigieg’s campaign has promised photos to people who spring for $500 or $1,000 tickets to some grass-roots fund-raisers. At one recent event, those who paid less could have left with something a bit less authentic: a selfie with a life-size picture of Mr. Buttigieg and his husband.

In a primary race where Democrats have two dozen candidates to choose from, a personal moment with the candidate can make a difference. For Ms. Warren, the interactions may also help dispel any preconceived notions about the approachability of a candidate who spent much of her career as an Ivy League law professor.

“It’s pretty smart,” said Doug Hart, 54, a teacher who waited in the selfie line in Lansing with his son, “because you got hundreds of people, they’re going to post them on Facebook, and you know what? They’re going to feel this personal connection.”

“Selfies” with Ms. Warren that were shared by voters.

At Ms. Warren’s campaign stops, her speech to the crowd is only the first half of a two-act production. What comes next, and can last just as long, is the Warren selfie line, a campaign-trail innovation for the age of Instagram.

Ms. Warren’s campaign estimates that she has spent about 107 hours taking pictures in selfie lines since entering the race — the equivalent of working 9-to-5 for 13 days. At one event in Iowa, she continued posing for pictures in the midst of a tornado warning.

“I have time to do this because I’m not spending hours and days and weeks with big-dollar donors and corporate lobbyists,” Ms. Warren said. “I’m not running around the coasts trying to scoop up as much money as I can. That leaves a lot more time for selfies.”

Ms. Warren is one of two key figures in the selfie line. The other is Nora Kate Keefe, 29, who serves as Ms. Warren’s body woman — the aide who is always close by the candidate’s side. She is also the campaign’s go-to selfie line photographer.

“I took on the clicks, as you’d say,” she said in an interview.

Ms. Keefe speaks in selfie-line lingo. “It really starts with line prep,” she said, explaining the mechanics of the undertaking. “Then there’s the bag push,” she said, referring to the person who takes bags and coats from people, so they do not fumble with them while meeting Ms. Warren.

One of Ms. Keefe’s signature techniques is to take photos throughout a voter’s interaction with Ms. Warren — not just when they pose for a picture. Voters are then pleasantly surprised to find a collection of pictures showing them meeting Ms. Warren, rather than a single snapshot.

In Lansing, the selfie line stretched all the way to the back of the gym where the event was held. Ms. Warren spent more than an hour posing for pictures, and about 800 of the 1,700 people at the event stayed to get a photo, her campaign estimated.

For some voters, their brief encounter with Ms. Warren was an opportunity to mention something important to them. Two law students were in their second Warren selfie line of the year, and even spent precious time showing Ms. Warren a photo from their first meeting. A woman in her 70s said it was among the highlights of her life — and she had just seen “Hamilton” twice.

For Stephanie Kittleson, 69, a retired teacher, the saying did appear to come true: A selfie was worth a thousand words. “I got to pose for a picture and I got to hug her,” she said. “You can tell she’s not a bunch of words.”