MOST OF US don’t notice someone’s mode of dress unless it’s particularly unique. It’s usually pretty easy to classify someone, based off of their clothing, into some category or another. I, for example, wear far too much flannel in the winter, and occasionally put on skinny jeans, so in the winter, I come off as a hipster. But come summertime, I wear t-shirts, cargo pants, and Birkenstocks, so I’m quickly classified as a bro. It’s a fun changeover from season to season — spring cleaning is called “pulling out the douche clothes” in my house — but I’ve never looked particularly hard to find other people who look like me.

It turns out, there’s probably a lot. People may think they’re dressing uniquely, but they almost certainly are not. Hans Eijkelboom, a Netherlands-based photographer, has made a habit of photographing people who are dressed alike in a single city on a single day. The results are amazing.

Eijkelboom has been doing the project for over twenty years and has just published a book called People of the Twenty-First Century. The book spans the years from 1993 to 2013.

“The process,” Eijkelboom told The Guardian, “is simply that I walk to the centre of the city where many people are. Then I walk around for 10 to15 minutes. When something in the crowd intrigues me or touches me, I decide that will be the theme of the day. Then I start photographing for two hours. Many times, it goes wrong: I don’t see anything, so I don’t photograph that day; or I go to the city, see my subject, start photographing and, surprisingly, in the next two hours, never see my subject again. And then, for that day, there is no photo note.”

The photos are totally candid. Eijkelboom rigged his camera so that he could take pictures without people noticing. He places it around his neck and had a wire trigger in his pocket so people can’t see that he’s taking a picture.

“When you walk in the city and look through the viewfinder,” Eijkelboom explains, “people say, ‘What are you doing? Why this photograph?’ And so on. I don’t have time to talk about what I’m doing, I want to get it done in two hours.”

Eijkelboom found that people tend to form “tribes,” in which the members of the tribe wear a similar uniform, but what’s often interesting is the tiny differences in the uniforms. People may be alike in many ways, but it’s the nuances that make them different.

“When you now go to the Kalverstraat in Amsterdam,” Eijkelboom says, “everybody has their own individual message on their T-shirt. But on the other hand, they all look the same, because they are all people with a message on their T-shirt.”

Though his book is now available, Eijkelboom is not quitting the project just yet. He intends to keep doing it for as long as he can.

Photos via My Modern Metropolis.