The history of t-shirts is a history of the 20th century. Originally they were mainly undershirts, though extensive military service due to WWII (where it was more common for hard working soldiers to spend their off duty time in t-shirts) made them more accepted as everyday casual clothes in civilian life. Starting in the 1950s movie heart throbs such as James Dean (in Rebel Without a Cause, 1955) and Marlon Brando (in Streetcar Named Desire, 1951) increased the popularity of the plain white t-shirt and drove it to a near iconic status as a "look". Combined with the counter culture trends of the '50s, '60s, and '70s the era of the full suit as everyday wear ended, and the rise of more casual wear and the t-shirt began.

Logo tees had existed for decades (there are even some examples within the Wizard of Oz movie) but they didn't become a pop culture phenomenon until fairly late in the 20th century. Starting in the '60s there was an explosion of expressive "statement" t-shirts often with screen printed patterns on the front. This is notable because it's a transition of clothing from simply a garment or a fashion statement (say, with a patterned fabric perhaps) to making them a personal billboard suitable for displaying any message (political, personal, cultural, aesthetic, etc.)

During WWII screen printing had undergone something of a boom due to its use in the quick reproduction of informative and propaganda posters. After the war it saw continued development as an art form, with Andy Warhol's work being a particularly notable example. Screen printed t-shirts started becoming more and more popular through the '60s, by the '70s they were common everyday wear, at least for some. Increasingly wearing a t-shirt became a way to project to the world your status as someone who could flaunt traditional fashion norms, especially in a work environment.

The '70s also saw many dramatic transformations as young innovators entered the scene and transformed (or built from scratch) entire industries and art forms. The invention of the microcomputer ushered in the advent of the personal computer and the video game system, bringing with it a revolution of the computer and home electronics industry. Apple Computer was the fastest growing company in history during the late '70s and early '80s, for example. Movies like Jaws and Star Wars ushered in a new era of blockbuster film making by young gun movie directors only fresh out of college. Atari. Intergalactic Digital Research. Microsoft. These were pioneering computer companies staffed by talented and powerful individuals who helped to normalize more casual attire and work environments. Even in 1980 IBM still had a strict dress code, but elsewhere workers, managers, and even CEOs and corporate presidents were wearing jeans, long hair, facial hair, and yes even t-shirts in the office and to important business meetings. At the same time new art forms such as punk, rap, hip-hop, skateboarding, and break dancing embraced a more casual "streetwise" aesthetic. More casual clothing become something of a cultural marker or status symbol, aligning yourself with the new wave of younger innovators, business leaders, and artists.

By the mid '80s logo and statement t-shirts were extremely common, especially among the "youth". From the Atari logo to "I (heart) New York" or "FRANKIE SAY RELAX DON'T DO IT" screen printed logo/statement tees were increasingly just one other component of standard American and western culture. However, it was not until the '90s that "self-referential" brand logo wear became commonplace, with the logo of the maker of the shirt (or other clothing item) being the message itself. Athletic brands (Nike, Adidas, polo, surf companies, etc.) were some of the first to become popular self-logo clothing, spreading into other areas and eventually infiltrating even luxury brands. Levi's, of course, had long had a lock on being a highly recognized and prestigious clothing brand, especially as jeans became wildly popular. Rap and hip-hop "street culture" began elevating athletic and luxury brands to status symbols (in 1986 Adidas gave Run-DMC a million dollar endorsement deal, for example) and mainstream culture followed along.