Though the Cooper Underwear Company popularized the crew-neck shirt, they did not invent the style.
The shirts evolved out of the long johns that men wore in the 19th century, when a number of garment makers experimented with methods that would allow the fabric to stretch over the head and then snap back into shape.
In the 1890s, the cotton pullover still looked like underwear to most people and wearing it in public was considered scandalous. Lawmakers in Havana went so far as to ban the public display of any underwearlike top, and so laborers had to toil in the heat wearing long-sleeve shirts with buttons. But gradually, the crew-neck caught on.
In 1920, the garment was reborn under another name, thanks partly to F. Scott Fitzgerald.
According to the Oxford English Dictionary, the author was the first to use the word “T-shirt” in print; it appears in the novel “This Side of Paradise,” in a list of accouterments that a character carries with him to boarding school.
Fitzgerald seems to have assumed that the idea of a “T-shirt” (so named, presumably, because of the shirt’s shape) would be familiar to readers and that they would associate it with the “white-flannelled, bareheaded youths” of New England prep schools. By the 1940s, T-shirts had become ubiquitous in high schools.
A newspaper columnist named Nancy Pepper wrote that teenagers owned closets full of T-shirts and customized them with sew-on patches and fringe. She reported that some high-school boys even used their T-shirts to advertise that they were available for make-out sessions; around the necklines of their shirts, the boys inscribed the words, “Neck here.”
By PAGAN KENNEDY SEPT. 20, 2013 New York Times