By Sandi Moynihan

ARLINGTON, Virginia — 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.

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.

According to a 2014 Gizmodo article, 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 make 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.”

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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.

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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.

3/3 Photos

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.

In 1905, the U.S. Navy helped popularize the T-shirt by adopting it as a part of its uniform just in time for World War I. 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, 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.“

Each year, thousands of service members at USO centers around the world – from Alaska to Afghanistan – vote for their favorite July 4th T-shirt design. The tradition provides a perfect way for you to support USO centers and show that you’re a Force Behind the Forces. Here’s how you can get your 2017 July 4th T-shirt designed by our troops.