Stewart Geekie and his wife Donna started the Antique Willys Association more than five years ago when they noticed there were tonnes of clubs for off-road Wrangler and Grand Cherokee enthusiasts, but none for fans of the original Jeep.

The Alberta couple – who own three classic Jeeps, including a 1946 CJ-2A and an MB imported from the Philippines – soon realized that traditional car club “show ‘n’ shines” didn’t make much sense, since their members’ Jeeps were mostly ex-military vehicles with dull paint jobs.

“We call them ‘show ‘n’ tells’ instead,” explains Stewart, “since everybody wants to know about them wherever we go. Even kids recognize the classic Jeep grille immediately.”

Willys-Jeep owners everywhere can, we’re sure, sympathize: the Jeep’s seven-slot grille is nothing short of an automotive icon, and likely the most well-known vehicular design element in the world.

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In the summer of 1940, the U.S. Army asked automakers for bids on a “light reconnaissance vehicle” contract, to replace the military’s Model T-based trucks.

American Bantam, Willys-Overland and Ford Motor Company each came back with a prototype: Willys’ Quad won out in the end. But the company couldn’t manufacture enough of the Quads – later renamed the MA, then the MB – to meet the Army’s demand, and so Ford was roped in to help turn them out.

The Quad/MA, along with early MBs, came fitted with a “slat grille,” simply a series of about 20 bars welded in front of the radiator. To speed up production, the stamped-metal grille from Ford’s GPW version of the Jeep was fitted to the MB in late 1941.

That grille, designed by Ford engineer Clarence Kramer, featured nine vertical slots, and was lighter and cheaper to produce than the standard Willys grille. When the first civilian Jeeps appeared for sale in 1946, the slots stuck, though Willys went from nine of them to seven.

In pictures: the Jeep Wrangler’s grille

First- and second-generation civilian Jeeps were built until 1953, and largely mimicked the design of their military counterparts. The CJ-3B of ’54 through ’68 was no great departure, but did feature a taller grille than the Army Jeep to clear the new Hurricane F-Head four-cylinder engine.

The 1955 CJ-5 debuted around the same time, and was the first Jeep to pass through a styling studio, says Jeep’s current chief designer Mark Allen. But the first CJ to get a major redesign was the CJ-7 of 1976.

Willys-Jeep, which at this point was owned by AMC, also fit some other models with the seven-slot grille, and its appeal was starting to show. The slotted-grille Kaiser Jeepster Commando was doing well until they fit an eggcrate grille to it in 1972 and sales plummeted.

The automaker felt plenty of hate, too, in 1987, when Jeep, recently bought by Chrysler, debuted the Wrangler YJ. This was the first Wrangler with square headlights and a bend in the grille—enthusiasts did not like it. Allen says they still get angry letters about it.

Jeep “finally got seven-slot religion” in 1996, says Allen, when the retro-styled Wrangler TJ was introduced. Five short years later, they levelled a lawsuit at Hummer for using a seven-slot grille on its H2—and lost.

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Mark Allen has headed Jeep design since 2009, and says the seven-slot grille, nicknamed ‘Sarge’ by fans, really helps define the entire Jeep lineup.

“The seven-slot grille is so integral to the Jeep brand it’s not even questioned [that a new Jeep will have it],” he explains. “It’s become so iconic it upsets me we still feel compelled to put a ‘Jeep’ badge on the front of a Wrangler. It’s just not necessary.”

While the grille on the current Wrangler JK isn’t too different from the TJ’s, Allen notes the fact it lives on a separate body panel “nibbles away at [his] Jeep soul.”

“Until 2006, the grille sheet metal held up the hood, radiator, fenders—everything was bolted to that. Now it’s a decorative piece of plastic.”

The hardest but most fun part of working with the seven-slot is dressing it up for premium Jeeps, Allen says. “On a Wrangler or Patriot, it’s pretty basic, but once you get up to a $60,000 Jeep Grand Cherokee Summit Edition, you’ve got to add some gingerbread to make that a nice piece.”

He also gets to play with the grille a little on those vehicles. “The Wrangler crowd I fear a little bit—there’d be pitchforks and torches if we screwed it up,” Allen remarks. “Everything else feels pretty safe. So for the new 2014 Cherokee, for example, we put a bend in the grille to make it recognizable.”

(Willys enthusiast Geekie has heard people say “it looks like an elephant sat on it.”)

But it is nevertheless a seven-slot, a design element that Allen says owes its enduring appeal to how simple and functional it is, and that is here to stay.

“Whenever we start any design work on any new model, it’s just acknowledged it’ll have a seven-slot grille,” he says. “The slots’re here and they’re very vertical now, and as long as I’m at this desk, they will remain so.”