The T-shirt is one of the beacons of American casual fashion. Popularized by U.S. Navy sailors during the first two world wars, the T-shirt has become an essential element of the American wardrobe.

In 1913, the U.S. Navy issued short-sleeved, white cotton crewneck undershirts to sailors. Sailors returning from World War I (1914–18) had grown to prefer the T-shirt to the woolen undershirt that had been the most typical undergarment since 1880. The popularity of the garment grew. By World War II (1939–45), twelve million men were wearing the shirts. News photographs and newsreels showed sailors and soldiers working in only pants and T-shirts. Underwear was exposed to the public for the first time. America had become quite used to the display of American muscle under a thin layer of white T-shirt by war's end.

Although the military persuaded America to embrace the T-shirt as an essential element of a...