1972, WGBH presented The French Chef and The Mod Squad with open captions, meaning they were burned into the video and couldn't be turned off. However, the major networks were reluctant to having open captions on their programs. As a result, PBS began testing two different methods of closed captioning. The first was created by the National Bureau of Standards (NBS) and was known as the "Line 21" method because it placed captions on a previously unused part of the broadcast bandwidth. The other was a system that broadcast the captions off the edge of the screen. The "Line 21" method was chosen and is still in use today.

The first closed captioned television series were broadcast on March 16, 1980. These included The Wonderful World of Disney (NBC), The ABC Sunday Night Movie (ABC), and Masterpiece Theatre (PBS).

In 1982, the Academy Awards show was the first program to be captioned live using realtime captioning techniques.

In 1990, the Television Decoder Circuitry Act mandated that all televisions manufactured for sale in the U.S. after 1993 must contain a built-in caption decoder if the picture tube is 13" or larger.

In 1996, Congress passed the Telecommunications Act. The Federal Communications Commission (FCC) adopted rules requiring closed captioning of most, though not all, television programming. The rules became effective January 1, 1998. See the FAQ page for a detailed explanation of this mandate.