Some of those holes are intentional—and they're doing way more than you think
When I first got this assignment, I laughed. Wait, you mean not all stop signs with holes are from target practice? I spent a lot of my childhood in rural backwoods areas, so I just assumed every sign eventually became Swiss cheese courtesy of someone’s Saturday-afternoon hobby. Well, I was very wrong—and also apparently driving around in a total oblivious fog for decades.
Sure enough, once I started really paying attention to road signs (um, yikes?), I did notice a few stop signs with perfectly symmetrical holes that looked nothing like bullet damage. These were neat, circular cutouts punched into the red metal around the bold white “STOP” letters, placed with the kind of precision that says “intentional design choice” and not “Billy Bob’s beer can substitute.” And just like there’s a reason why restaurant ice cubes have holes, those holes in stop signs were put there on purpose.
“Sometimes, holes are intentionally cut out from the non-message surface of the sign,” explains Paul Dorr, director of engineering design at the Traffic Group who has designed hundreds of intersections using stop signs. And, adds Samantha Keith of AWP Safety, a company that makes official stop signs, they’re put there for a reason that’s actually pretty smart.
So if you’re like me and never thought to look into these unusual design details before, buckle up (safety first!) and read on to find out the surprising reason some stop signs have holes.
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Why do some traffic signs have holes?
“It’s for aerodynamics,” Dorr says. “Holes are sometimes intentionally cut out of the sign to allow for wind to pass through the sign.” These so-called wind holes are strategically cut into the non-message areas of the sign (notice they never interrupt that critical “STOP” text) to allow wind to pass through instead of pushing against the entire surface like a sail.
This design choice is particularly common in coastal states where high winds are common or within confined spaces where buildings might create what Dorr calls a wind tunnel effect, magnifying wind speeds. It makes sense: A solid metal sign acts like a giant paddle in the wind, creating enormous pressure on the pole and foundation. As a result, it could blow down, get turned in the wrong direction so drivers can’t see it, or potentially even become a projectile. Punch a few holes, and problem solved!
How many holes is ideal?
There isn’t a standard number of holes used for this purpose, but Keith says that most signs with this feature generally have four to eight small, round perforations (usually 3/8 to 1/2 inches in diameter) placed symmetrically around the center or in a grid pattern. Others have three larger holes arranged in a vertical line, often near the center of the sign.
And scientists really geeked out to devise the best patterns. A 2020 study published in the journal PLOS One used computer simulations (basically, fancy virtual wind tunnels) to test different hole patterns. They blasted pretend signs with winds ranging from 49 mph to 101 mph—that’s tropical storm to low-end hurricane speeds. The winner? Holes about the size of a quarter to a half-dollar (1.2 to 2.4 inches), spaced far enough apart that they don’t weaken the sign too much. So yes, these holes are placed with legit scientific precision, not just randomly punched in by someone with a drill and too much free time.
Sign creators carefully calculate where to position these openings based on wind-load requirements and the sign’s total surface area, Keith says. The goal is to reduce wind resistance enough to prevent the sign from swaying like a metronome during storms, while still maintaining the sign’s structural integrity and visibility. But it’s a delicate balance between staying upright in a hurricane and making sure drivers can still see the word STOP.
When did these hole-y signs become a thing?
Before we dive deeper into this Swiss cheese metal mystery, let’s talk about where stop signs came from in the first place. The very first stop sign was installed in Detroit way back in 1915, according to Dorr. But don’t picture the iconic red octagon we all know today—that original sign was a simple black-and-white square measuring just 2 feet by 2 feet. The stop sign didn’t get its signature octagonal shape until it was standardized in 1935, and the red background didn’t become official regulation until 1954.
As for the intentional wind holes? Engineers experimented for a while with perforated sign panels to help reduce structural stress caused by wind and weather, but it was more trial and error than science. Then, in 1994, the American Association of State Highway and Transportation Officials (AASHTO) issued guidelines for federal wind-load standards that specifically addressed how to design signs that could withstand extreme gusts and wind pressure.
The practice never really became widespread or standardized, though. States like Wyoming reportedly had local road crews drilling holes in signs to combat their notoriously relentless winds, but these homegrown solutions were never formally adopted as official engineering standards. It wasn’t until computer technology advanced enough to run sophisticated wind tunnel simulations and computational fluid dynamics models (like that 2020 PLOS One study) that engineers could precisely calculate the optimal size, spacing and placement of holes for maximum effectiveness.
How common are these signs?
These days, perforated signs remain optional and uncommon. (The ones I saw back in the day were up a windy canyon.) “These are not required by the MUTCD,” says Keith, referring to the Manual on Uniform Traffic Control Devices, the federal guidebook that sets standards for all road signage. “They’re optional and mainly used in high-wind regions, construction zones or portable sign stands. Permanent municipal signs on sturdy posts usually don’t need them.”
Where will you mostly see them?
Geography matters when it comes to hole-y stop signs. You’re most likely to spot them in coastal areas where strong, sometimes hurricane-force winds are routine, like Florida and Louisiana. In addition to ocean and gulfs, areas near large lakes may sport these signs. You’ll also find them in mountain passes, open plains and other areas known for gusty conditions, as well as in urban corridors where tall buildings create wind tunnel effects that would make even Mary Poppins think twice.
Construction zones and temporary work areas also commonly use perforated signs. These portable signs are often mounted on lighter stands with weighted bases, so they’re more vulnerable to being knocked over; the perforations help prevent that problem.
So those really aren’t bullet holes?
OK, let’s be real: Some of those holes absolutely are bullet holes. (See, my instincts weren’t totally wrong!) How can you tell what’s what? According to both experts I spoke with, it’s all about the pattern and quality of the holes.
“Signage with wind-resistance holes intentionally cut into them are symmetrically placed and not within the message area,” Dorr explains. “Signs that are vandalized (shot) will typically have nonsymmetrical holes that are smaller and randomly placed.”
Keith gets even more specific about what to look for. Intentional holes “will be deburred, clean punctures on the face of the sign. They will be evenly spaced, small, uniform size, often in a symmetrical pattern, and they are usually round and perfectly circular.” Vandalism holes, on the other hand, “typically will not be clean-cut punctures and will not follow a specific pattern. They will have visible entry/exit deformation, scattered placement, sometimes around the lettering or the center, and may have ragged, cracked or discolored rims.”
Even large-caliber bullets don’t typically create the neat holes you see in properly manufactured signs. They leave smaller entry wounds and potentially jagged exit damage on the back of the sign.
Do metal traffic-sign posts have holes for the same reason as stop signs?
Nope! The posts holding up traffic signs have holes to literally save your life. They’re part of what’s called “breakaway engineering,” and it’s one of the cleverest safety innovations hiding in plain sight on our roadways, Dorr says.
According to the National Highway Traffic Safety Administration, 7 out of 10 deadly single-car crashes happen when a vehicle runs off the road and slams into something solid—like a sign post. A rigid metal or wooden post can basically turn into a giant spear. Not good. Breakaway posts were invented to fix this problem. Instead of standing there like a stubborn tree, they’re designed to snap off or bend when a car hits them. The federal government made these mandatory starting in 1998 for major highways, and by 2000, they said every sign in the “clear zone” (that’s the area next to the road where a driver might swerve back onto the pavement) had to use breakaway posts. No exceptions.
So how do those holes make posts break away? Some are designed to bend like a straw. Others have holes drilled at regular intervals up and down the entire post (not just at the bottom) so they’ll crumple when hit. The really big posts use something called a “slip base”—imagine a post sitting in a cup filled with concrete. When a car hits it, the post slides right out of the cup and tips forward so the car can pass underneath. It’s like watching a waiter drop a tray but the tray lands flat instead of crashing.
And yes, these safety measures actually work. Minnesota reported significantly fewer serious crashes after switching to breakaway posts, and Texas saw a 25% drop in deadly crashes involving signs after breakaway posts were installed on rural roads. That’s a lot of lives saved by some strategically placed holes. It’s a perfect example of invisible infrastructure working exactly as intended—you never notice it until the moment it saves someone’s life.
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At Reader’s Digest, we’re committed to producing high-quality content by writers with expertise and experience in their field in consultation with relevant, qualified experts. We rely on reputable primary sources, including government and professional organizations and academic institutions as well as our writers’ personal experiences where appropriate. For this piece on stop signs with holes, Charlotte Hilton Andersen tapped her experience as a longtime journalist who often covers common curiosities and fun facts for Reader’s Digest. We verify all facts and data, back them with credible sourcing and revisit them over time to ensure they remain accurate and up to date. Read more about our team, our contributors and our editorial policies.
Sources:
- Paul Dorr, director of engineering design at the Traffic Group; phone interview, Oct. 20, 2025
- Federal Highway Administration: “Manual on Uniform Traffic Control Devices (MUTCD)”
- American Traffic Safety Services Association: “Signs”
- Samantha Keith, branch manager at AWP Safety; email interview, Oct. 21, 2025
- PLOS One: “CFD simulation study on wind load of perforated traffic sign board”
- Federal Highway Administration: “FAQs: Breakaway Sign and Luminaire Supports”
- National Highway Traffic Safety Administration: “Run-Off-Road Crash Statistics”
