July 1 is a huge day in American history - in 1963, it brought America zip codes, a fundamental part of our postal service system.
Possibly, even more important, however, was the introduction of the Sony Walkman in 1979, which sold out its entire stock of 30,000 units by October of the same year, according to The Atlantic.
The 'Walkman' was a hand-held playback device with headphones - the late '70s version of an Ipod or MP3 player. It was the premium device of its era.
The Walkman set the stage for MP3 players, such as MPMan - the first portable digital audio player, which debuted in 1998 - and the Ipod, which debuted in 2001.
