Some mysteries will never be solved. Who was Jack the Ripper? What sunk Atlantis? Where did Amelia Earhart go?

Today, you can scratch one of the most maddening of these enigmas off your list: we finally know why dress shirts often have a little loop of fabric sewn into the back. Get ready for a little lesson in fashion history, for the answer to this conundrum lies in the past.

The Rise of the Preppy Style

According to the Gentleman’s Gazette, the fashion offshoot that we call “preppy” started in the early 1910s. That’s when folks who went to Ivy League schools decided they wanted everyone to know they went to Ivy League schools—it was a status thing.

The market always responds to desire, especially where fashion is concerned. Therefore, A brand called J. Press started selling smart, semi-casual clothing around the famous universities on the East Coast. Seeing the success J. Press had, Brooks Brothers quickly got in on the game too. Soon, an unofficial uniform for Harvard students developed. In fact, that’s where we get the term “preppy”—you know, “prep school.”

Lots of these clothes catered to the sporty young collegiate types. You know, the ones involved in sailing, golfing, and tennis. There’s a definite nautical influence on Preppy style.

It wasn’t long after that people wanted to share the same look. By the 1980s, “preppy” was a recognizable style in the high schools of the Midwest. Just look at Zack Morris from Saved by the Bell. Remember what his sporty buddy Slater called him? (Slater called him “Preppy.”)

One mainstay of the preppy style was a pressed button-down shirt. Beginning in the 1950s, these shirts often appeared with a telltale loop sewn into the back, just between the shoulders.

What’s With the Loop?

We’re not historians, but we trust Today. The intrepid reporters of the daytime talk/news hybrid looked into the history of the ubiquitous shirt loop and published a website piece that explains the most accurate theory of this oddity’s origin.

According to Today, the whole thing started with a fashion label called GANT. At some point in the 50s, GANT started selling dress shirts with the iconic loop on the back. The company called them “locker loops,” which hinted at their intended purpose.

Remember the association with college sports that launched the whole preppy look? With locker loops, students could hang their shirts in a locker while they batted around the birdie or whatever. Then, post-workout, they’d be able to throw on the unwrinkled shirt and get back to class.

Eventually, locker loops took on a life of their own. College men would cut the loops off when they began a serious romance, and flirtatious women reportedly pulled the loops off of the boys they liked.

As the rest of preppy culture flowed into the mainstream, the locker loop went with it. Now we all have them. So there’s something for your fact file.

Now, if we could just get back to that Atlantis question…