This post contains images that are NSFW.
After a long day of driving their off-roaders and quad bikes into thick quagmires of mud, the “mudders” who swarm to 4×4 Proving Grounds in Maine go into the woods to get naked and party till they can’t remember anything. These gatherings, which happen sporadically throughout the year, aren’t exactly laden with subtext, and for the last five years photographer David Horton has been capturing the primal shenanigans that unfold there.
Amusingly, Horton first stumbled on Proving Grounds by accident, while lost and trying to find his way to another event he wanted to cover in Maine. Half a decade in, he’s starting to feel like one of the family. “I felt like a rock star this year with women running up and hugging me, welcoming me back,” Horton says. “Apparently, I made an impression.”
After first featuring his work back in May—perhaps you remember “Crazy, Horny Mud Truckers”—VICE asked Horton to go along to this year’s big Labor Day party, and his photos from the 2025 event are dotted through the interview below.
After the end of the Q&A, you’ll find some classics from previous years that we raided from Horton’s vaults.
VICE: For the uninitiated, can you explain what the 4×4 Proving Grounds event is?
David Horton: Proving Grounds is a 123-acre, private mud park in Lebanon, Maine where off-road enthusiasts go to race, camp, and party in the mud for multiple days during Memorial Day, Fourth of July, and Labor Day weekends.
What kind of thing tends to happen there?
People bring campers, RVs, trucks, and trailers and hunker down for the long weekend. There are three race tracks where formal mud races take place but more interesting to me are the various mud pits throughout the property, where people fly with reckless abandon. There are a number of military trucks around to pull vehicles out of the mud when they inevitably get stuck.
How did you discover the event?
I discovered this event with a Lebanese photographer friend of mine who was working on a photography project photographing all the towns named “Lebanon” in the United States back in 2019.
How did this year differ from previous years?
Each year is different, as are the number of attendees. This year was probably half the size of some previous years. Trucks Gone Wild, a very large organization, was not involved this year. When they’re involved, they draw larger crowds from up and down the East Coast. This year appeared to draw more of a local crowd.
This is the second time your photos from Proving Grounds have featured on VICE.com. It seems this year the key tenets of the event remain the same—it’s very white, very Republican, pro gun, pro oil, pro partying. Are there any hidden nuances to the event that people don’t see?
Almost across the board, the attendees are white, Republican, pro-gun self-proclaimed “rednecks.” However, in my experience, there is a very strong sense of community. This is a serious subculture. The majority of people are very nice and welcoming. I’ve never felt personally threatened. People can see that I’m a serious photographer, committed to capturing the authenticity of the culture. I’m assertive—you have to be—and sometimes put myself in risky situations to get some of the shots. They respect that; I feel the respect.
What are the core rituals that Proving Grounds people hold dear?
The core rituals all involve mud: racing in the mud, diving in the mud, wrestling in the mud, dancing in the mud. Another important ritual, which is very similar to what happens at Mardi Gras, is women (and men) bearing naked breasts in exchange for bead necklaces. The phrase the “mudders” use is “Dump ‘em out!” There are T-shirts, flags, and signs with the phrase everywhere. Groups of people chant the phrase and naked breasts usually appear.
This may be a stupid question, but how does everyone end up naked?
When the sun goes down, private parties throughout the property begin. Word gets out during the day which camps are holding the best parties. The parties are taken very seriously. People are setting up elaborate stages, lights, and sound systems throughout the day. The parties usually involve pole dancing. As the evening progresses and more alcohol is consumed, the clothes come off all together and audience participation increases.
Is there any actual al fresco sex at the event or is it mostly a performance?
I’ve never witnessed a full-out orgy. It’s mostly performance that is encouraged to push boundaries and limits.
What is the overriding atmosphere at the event? Do people welcome your presence?
My presence is very welcomed and respected. I felt like a rock star this year with women running up and hugging me, welcoming me back. Apparently, I made an impression. From the very beginning, I am very generous with sharing pictures. People are constantly asking me where they can get the pictures. I hand out business cards so people can contact me. I shoot some pictures just for people. The pictures I really care about are just for me. The ones I’m interested in aren’t usually the ones they’re interested in.
Will you be going again next year?
I’ve been shooting this event for over five years. My goal was always to make a book of the work, which I think I have enough material for now. I’m not sure if I’ll continue to shoot this event or put my energy into making the book. This is just one of a half dozen long-term projects I’m working on.
Find more of David Horton’s work at HortonPictures.com.
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