Cool t-shirts are a part of American culture, or at least of the last 60 or 70 years. World War II brought the first images of cool tshirts into American living rooms, with the soldiers working in their cotton undergarments to keep cool. Now the idea of cool has taken on a whole new meaning - cool t shirts are the ones that look stylish, effortlessly hip and always comfortable.

For a closer look at when those plain white cotton undergarments went from wartime uniform to fashion staple, all you have to do is look at what young men were wearing in the 1950s. Guys like James Dean and Marlon Brando made cool t-shirts famous, in movies like "Rebel without a Cause" and "A Streetcar Named Desire." Anyone who is familiar with these films remembers the cool tshirts Brando wore, and what a stir it caused in the fight scene where his shirt was ripped open.

In the 1960s, cool t-shirts took on another meaning entirely, with new colors and designs hitting the streets. Whereas the cool t shirts of the 1950s were the plain white variety, psychedelic tie-dyed tees were the coolest fashion necessities for the flower child generation. In the 1970s, however, it became more popular for people to wear cool tshirts with catchy phrases on them, like the famous "Have a Nice Day" shirts with yellow smiley faces.

In the 1980s and 1990s, neon colors were all the rage, and people tried new things like heat-sensitive, ripped or layered tees. All sorts of creative shirts are being manufactured since the millennium, too, with pop culture references and conceptual designs becoming more popular than. In any case, the t-shirt should remain cool for decades to come.