I think this is actually the recent-ish thread people are thinking of. It took a little while to turn up because the thread title is 30 years ago now versus 30 years ago 30 years ago and not something about Back to the Future: http://boards.straightdope.com/sdmb/showthread.php?p=13354641
I mentioned the linked thread to my mother (born in 1955) at the time, and she agreed with those who’d said the social changes from 1955 to 1985 were much bigger than from 1985 to today.
Youse guys could be right about the greater social changes in the prior 30 years than in the most recent 30 years. But could it also have something to do with the fact that more of us *remember *the last 30 years, but not the previous 30 years? The fifties are just history to me; the eighties through today are my real life and therefore not so mysterious.
Could be, but Sam Stone didn’t post in that one. Either way, no harm in us showing both links.
Like I said, my mother was born in 1955 and while she doesn’t remember the '50s well she was an adult prior to the '80s and certainly remembers what the world was like before 1985. One of her examples of how the world has changed is that when her older sister, who was making good money as a fashion designer, wanted to buy her first house in the late '60s then she had to get my grandfather to co-sign all the papers. No one wanted to give a mortgage to a woman. If she’d been married then her husband could have handled such things, but since she was still single her father had to do it. Never mind that she actually made more money than my grandfather, a farmer.
While a “colored mayor” might have seemed laughable to a white man in the 1950s, I don’t think many Americans in 1985 would have considered the idea of a black president (or a woman president) to be so far-fetched. Many '80s Americans would probably expect this to happen in the relatively near future. An openly gay president or a non-Christian president might be more surprising to them, but that would be surprising even now. Speaking of gay rights, I think my Clinton era teenage self would have been surprised to learn how slowly things were going to move on that front. I wouldn’t have expected that same-sex marriage would be recognized in only a few states as late as 2011.
Arnold Schwarzenegger. Though he had been in a few movies by that point, he still wasn’t that well known and unless you followed bodybuilding, there’s a good chance you wouldn’t even have heard of him.
Too bad he wasn’t still governor, though, because it might have made for a good gag:
Doc: OK, who’s governor of California in 2011?
Marty: Arnold Schwarzenegger.
Doc: The bodybuilder??!! Who’s lieutenant governor? Lou Ferrigno?
Didn’t Al Gore’s son get in trouble for driving his Prius 100 miles an hour?
True, but Jerry Brown works almost as well.
“Who’s governor of California in 2011?”
“Jerry Brown.”
"He’s still the governor?
…complete with Shaky-Cam?
Marty goes into a retro '50s diner and orders a Pepsi Free.
Bartender: “WHAT?!? You want a Pepsi, free? Why should I give it to you for free? I work for a living!”
Marty: “No, I want a Pepsi Free.” [points to the advertisement on the wall]
Bartender: [sheepish] “Oh, right. Sorry, those just came on the market, I keep forgetting.”
How about a play on “Pepsi One” or “Coke Zero”?
Marty: “I’ll have a Pepsi One.”
Waiter: “Okay, that’s one Pepsi…”
Marty: “No, a Pepsi One.”
Waiter: “Yeah, I’m only going to bring you one, don’t worry.”
Hmmm, when did people stop smoking openly on the Tonight Show?
Lamia-I bet the reason people in the '80’s would’ve been unsurprised by an African-American or female President is because people like: Liz Dole, Jesse Jackson, and Geraldine Ferraro were on the scene.
Your mother is right.
The White Stripes are hardly a new sound. If anything the kids would think he’s playing some sort of 60s psychadelic rock.
Even hip hop would have been popular since 1979 (Rapper’s Delight by The Sugerhill Gang).
I say say he would sing “Born this Way” by Lady Gaga. Then some girl would be on the phone with her cousin Madonna.
Also, you people seem to forget Rev Jesse Jackson ran for President in 1984. The idea of a black president wasn’t that far fetched (at least not because he was black).
“You people”? 
“War in Iraq? But they’re our friends!”
Or a suspicious 1981 authority interrogates the time-tossed 2011 teenager:
Authority: “How do you know these things? Are you a spy? Right outta East Germany?”
Teenager: “What the hell is an east Germany?”
Replacing the Delorean with a Prius or Tesla would cause problems with part III: One of the challenges Doc faced in the 1880s was that while the flux capacitor was powered by Mr. Fusion, the car itself still needed gasoline to get up to 88 MPH. With an electric or hybrid car, though, it wouldn’t be hard at all to hook the Mr. Fusion in to the drivetrain electrical system.
See post #32.
You could say that the time circuits needed to draw all the power of the nuclear reaction/lightning/Mr. Fusion, which barely provided enough as it was…though I admit, if I was doing this as a remake, I’d want to add some further twist of my own. (Maybe move Part III up to 1915, and have to mount the Prius/Tesla with a damaged chassis up to the only aircraft that could lift it and make 88 mph in a dive…an early zeppelin. Yeah, that’s lousy and full of holes, but I came up with it in 30 seconds. 
)
Heck, see post #24: