CHICAGO — An @ewarren selfie line has formed at O’Hare International as she awaits a flight to Cedar Rapids. She was on the phone and when she hung up a crowd started to form. pic.twitter.com/eC48ZFB9qo

As Warren traveled to Iowa on Thursday, a small crowd of travelers gathered around her at an O’Hare gate and formed a line to take photos, according to CBS News reporter Ed O’Keefe, who witnessed it unfold.

Senator Elizabeth Warren’s “selfie lines” are becoming so well-known that they appear to be popping up spontaneously, including at Chicago O’Hare Airport this week, CBS News reported.

O’Keefe reported that the crowd included airport employees, travelers, and even flight crew members.

WATCH: The best part of this is observing passersby as they realize it’s her and either get excited or seek thoroughly unimpressed: pic.twitter.com/awYWIXdVeJ — Ed O'Keefe (@edokeefe) September 19, 2019

The Cambridge Democrat has been holding so-called “selfie lines” throughout her campaign, staying behind after her rallies end to take photos and meet with supporters. (“Selfie line,” of course, is a bit of a misnomer, since an aide is the one snapping the photos.) During a rally in New York City that drew a campaign-estimated 20,000 people on Monday, Warren stayed for more than four hours taking photos and meeting attendees.


She later told MSNBC’s Rachel Maddow, “Yeah, I was there four hours, but I’ll tell you what, so was the last guy in line.”

The lines have become such a mainstay of Warren’s rallies that they are increasingly well-organized, with campaign workers managing the line, according to the New York Times.

Warren was flying through O’Hare on her way to Iowa this week, where she’s campaigning along with nearly the entire Democratic field. The Globe reported Friday that among them, the field of candidates is scheduled to appear at 90 events in the state, including the Polk County Democrats’ Steak Fry.

Christina Prignano can be reached at christina.prignano@globe.com. Follow her on Twitter @cprignano.