Short answers, pulled from the story.
The United States Navy issued the first official T-shirts to sailors in 1913. These garments were simple white cotton undershirts designed strictly as undergarments to be worn beneath naval uniforms.
Actor Marlon Brando made the T-shirt a visible symbol of rebellion in 1951 when he wore a white T-shirt under an open shirt in the film A Streetcar Named Desire. This scene shocked audiences accustomed to seeing men in button-down collars and turned the T-shirt into a fashionable outerwear garment.
The concept of the printed T-shirt originated in Miami, Florida, in the early 1950s when companies like Tropix Togs began decorating T-shirts with resort names and characters. Sam Kantor founded Tropix Togs and secured the original license to produce shirts featuring Mickey Mouse and Davy Crockett in 1976.
The T-shirt became a medium for political and social expression in 1969 when psychedelic art poster designer Warren Dayton printed large, colorful political cartoons and images of figures like Cesar Chavez on T-shirts. This era transformed the garment into a walking billboard for the counterculture movement.
Two billion T-shirts are sold worldwide each year, making the T-shirt the most worn garment of clothing used globally. This ubiquity comes with a heavy environmental price due to the water-intensive production of cotton and reliance on pesticides.