When did the 80s really become the 80s?
The 80s didn't start on January 1st 1980, and it didn't end on December 31st, 1989. In calendar terms, yes it did, but not the 80s era as we know it. In fact, I would argue that the 80s really came into its own around 1983, and probably ended around 1986 before blurring into the 90s. The very early 80s and late 80s was more of a transition period from the 70s and into the 90s. It's funny to think about, but the 80s as we know it is really just a 3-year period between 1983-1986. Most of our 80s nostalgia is crammed into that 3-year period. Think about it, everything that represents the 80s in your mind probably came from the years 1983, 1984, 1985 or 1986. I'll list some examples below:
Politics: the Challenger Explosion, Iran-Contra, Chernobyl
Movies: Karate Kid, Back to the Future, just about every John Hughes film, Gremlins, Goonies, Breakfast Club, etc. Even though E.T. came out in 1982, the fashion was mostly from the 70s. Movies from 1983 and onward, however, had the more '80s' look.
Music: This is a no-brainer. First of all, MTV exploded during this time. I guarantee, just about every popular 80s song you can think of came from the years 1983-1986. Most of the 80s songs you hear during last call at any bar, came from 1983-1986. Not to mention, most of Michael Jackson's all-time hits came from that period (Thriller, Bad, etc.).
Video Games: NES launched in 1983, NES games took off in the mid-80s, and kind of slowed down in the late 80s as the Sega Genesis came onto the scene, and later, Super Nintendo
Computers: The Macintosh came out in 1984
Even if what I'm saying isn't entirely true, it is at least mostly true. Just about every artifact from 80s came from a single 3-year period between 1983-1986.