How the U.S. Military Made the T-Shirt the Most Popular Garment in the World

By Sandi Gohn

Almost everybody has a favorite T-shirt. For some, it’s an old Army PT shirt, carefully preserved after years of service. For others, it’s a patriotic USO shirt, worn proudly every Fourth of July.

T-shirts are something most people wear almost every day all around the world. But did you know that the history of the T-shirt, and its rise to global popularity, has roots in the U.S. military dating back to World War I?

The Early History of the T-Shirt

Given the T-shirt’s widespread popularity and its prominence in modern fashion, it might seem surprising that before World War II, the garment was considered a piece of underwear and was rarely worn as a piece of an outfit on its own.

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According to a 2014 Gizmodo article by Karl Smallwood, the modern-day T-shirt originated from a 19th century all-in-one flannel undergarment called the Union Suit. To stay cool during the warmer months, men started cutting their Union Suits in half, creating two under garments, one of which would evolve into the modern-day T-shirt.

Near the turn of the century, clothing companies started making the garment with lighter fabrics like cotton and nylon and began to sell just the upper portion of the Union Suit as its own piece of clothing, marketing it as a “bachelor undershirt.”

The T-Shirt Gains Popularity after World War I and World War II

In 1905, the U.S. Navy helped popularize the T-shirt by adopting it as a part of its uniform just in time for WWI. During the Great War, thousands of American service members across all branches were required to wear the T-shirt underneath their uniforms at all times, and many continued the habit of daily use after they returned stateside.

Even into the 1930s, the T-shirt wasn’t considered an appropriate undergarment for adults to wear in public, but that all changed after WWII, when millions of military veterans started wearing them as casual outerwear like they had while serving overseas.

As Smallwood notes in his Gizmodo story, the World Wars weren’t the only reason why the T-shirt became a worldwide phenomenon:

“The popularity of a T-shirt as an outer garment further surged thanks to Marlon Brando and his role as Stanley Kowalski in ‘A Street Car Named Desire,’ which featured Brando wearing a tight-fitting (as most were at this point), biceps-caressing T-shirt. Brando’s smoldering performance in both the play and 1951 movie caused a nationwide spike in sales of T-shirts.”

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This story was first published on USO.org in 2017. It has been updated in 2022.