I, for one, love pocket T-shirts. They're perfect for people who wear eyeglasses, like me (because I cannot see a thing without them). But glasses are not what they were originally designed to carry. In fact, it was cigarettes — and the pocket matched the precise measurements of the most popular box.
It's safe to say the tiny pocket isn't original to the T-shirt, however, since the product only hit the mass market as recently as the mid-50s. Chest pockets appeared on a top layer invented — and patented — two decades prior. Then, T-shirts were not something to be worn alone, but rather under a "union suit," a one-piece coverall workers wore year-round. It was most commonly made from wool and thus far too hot to wear in the summer months. Fed up with overheating, the story goes, someone cut the garment in half, leaving the top long enough to tuck it into the bottom. A-ha, the T-shirt was born.
But not so fast; wearing one on its own was still taboo. In fact, it was outlawed in some states. That was until it became standard issue in America's armed forces. In 1904, Army supplier Cooper Underwear advertised its "bachelor undershirt," a T-shaped shirt with a stretchy neck and a henley-like button configuration. But by 1915 the military abandoned buttons, because soldiers lacked sewing skills and struggled to replace missing ones. (True story.)
As such, the Army inched even closer to inventing the T-shirt as we know it. When soldiers left the service, they took their stock with them, and T-shirts became pedestrian — and very, very popular. First marketed to kids, the companies that manufactured them eventually catered to adults, too.
In the 1951 film A Streetcar Named Desire Marlon Brando wears a tight-fitting T-shirt with no front pocket. T-shirt sales boomed shortly after. In 1955, James Dean wore a T-shirt on screen, too, in Rebel Without a Cause. His was more in tune with today's shape, though: longer sleeves and a tighter crew neck, but still no pocket.
So how'd we get from outerwear with pockets — M-65 jackets, for example — to T-shirts with them, too? If plain T-shirts were popular (hence the famous men sporting them), why sully them with a pocket?
The small left chest pocket was first included in a patent filed on August 16, 1929 by John W. Champion of Evanston, Illinois on behalf of Chicago-based Reliance Manufacturing (who coincidentally held over a dozen military contracts at the time, too). He presented an illustrated pattern for an everyday shirt with asymmetrical pockets — one big one on the right side of the chest and a crested one on the left sized perfectly for a box of cigarettes. Called a "yamapoke" in Japanese repro circles, the pointed pocket was original to engineer shirts but were adapted by Champion for more common wear.
Surely Champion's original pocket was more robust — two-ply to keep the cigarettes off wet skin and with a clasp closure to block rain — but it set a precedent for pocket tees to come. And Reliance Manufacturing's tie to the military, where T-shirts (and, as such, surely T-shirts with pockets) first appeared is no coincidence. But the true origin remains unclear.
It's fair to say that pockets were probably carried over from outerwear to T-shirts because cigarettes were still plenty popular — especially with the subset of men that resonated with characters played by Brando and Dean. Today, the vice has faded from fashion but its impact on fashion has not.