Baltimore is probably one of the earlier cities in the US to do this with the creation of the inner harbor shopping area, after B’more a lot of other cities followed their example.
In Montreal, the Plateauis probably the example that comes to mind first; a formerly working-class neighbourhood which is now incredibly trendy and rather expensive. As an anecdotal example, a family member bought a 5-unit apartment building about 15 years ago for about $450 000. He recently turned down an offer for $1.2 million.
The Sud-Ouest, Ville-Marie and parts of CSL-NDG probably also qualify, to various extents.
I doubt you’re going to go into too much history or detail for a Cracked article, but the language/cultural and industrial history of Montreal basically makes any neighbourhood an interesting one.
When I lived in NYC, anything above about 86th street west was considered “iffy”.
Within a year, that moved up to anything above 92nd street.
By the time I moved away, that had moved up to about 97th street.
I can remember joking to friends I should buy a tenement in Harlem and just wait for it to become a hot area to live in. They all laughed and said, “Not in your lifetime…”
Sigh - wish I had had the money to do what I joked I wanted to do…
There are a LOT of areas in NYC that qualify. Park Slope and Williamsburg are prime examples. Also Carroll Gardens, and maybe Astoria and Washington Heights too.
I think there’s a section of downtown Atlanta that is highly gentrified, but don’t remember the name.
Anacostia (DC) is gentrifying right now, though I certainly wouldn’t call it “High-Rent” quite so soon. There are now areas that look like Stepford Wives suburbia - wow.
Yeah, DC’s transformation has been amazing. There was an aricle in the WaPo last week about the dramatic change in city services and influx of new residents.
In DC, there was also Swampoodle. It was an immigrant shanty town that was largely torn down to make way for Union Station. A large chunk of that area is being redeveloped as NoMa. It’s now mostly high rise office buildings but there are some luxury rentals that are coming in and some really expensive condominiums.
Additionally, according to this, Georgetown had deteriorated from the 1890s to the 1930s before reviving again.
Speaking of Baltimore, I seem to recall that Federal Hill was a slum in the 1960s and now it is fairly pricey.
Thanks for this. I live in SW Ohio, but grew up in Chicago and lived there 30 years, and I remember Uptown fondly. I lived there----and moved away----long before gentrification.
I used to eat at the Uptown Snack Shop every morning (Leland & Broadway) and was broken hearted when gentrification forced them out. (Three Greek brothers were there 50 years) I bar-tended at The Green Mill long before the white wine spritzer crowd showed up; when it was mostly Indians and hard-scrabble locals, and it was dangerous at the rear of the bar. We used to pay the police every night to some at 3:30 am to shag out the hold-outs/ belligerents.
I loved Uptown. I lived at Lawrence & Clarendon and used to take the L and walk past the Aragon Ballroom, and the dive bars across the street. (Sharon’s Hillbilly Heaven, and Saxony down the street)
I always laugh when someone says “I bought a condo in Buena Park”, and then I see its 12 blocks away in Uptown.
Park Slope and Carroll Gardens were never slums. Down at the heel, maybe. Even in the early 80s they were considered “nice” and desireable neighborhoods, relative to virtually all parts of Brooklyn (only Brooklyn Heights had more cachet) and most parts of New York City. They are fancier and more developed now than they were in 1982, but that’s because rising tide lifts all boats, not because Park Slope and Carroll Gardens were considered “slums” or “the ghetto” in the last 30 years.
Compare to East New York, which has been a for-realsies shithole from the 60s to until just a few years ago. The changes in East New York and Bushwick just in the past 5 years are impressive. I can remember driving down the Eastern parkway spur as a child and you’d see nothing but block after block after block of burned out vacants. Now there’s new construction, renovations, a supermarket, playgrounds in nice condition, etc.
Bed-Stuy is more thoroughly gentrified though. Once memorialized as someplace you’d walk around alone only if you were crazy (in the Billy Joel song, “You May Be Right”) it’s now very desirable.
Was the Fillmore in San Francisco ever really downscale? It’s now a solid block of condos and upscale commercial properties–complete with sidewalk plaques commemorating the well-known nightspots that got priced out of the neighborhood 
Heh, Hyde Park probably works too.
Areas of London you might want to consider:
Notting Hill
Islington
I don’t know much about either area other than anecdotal - these areas are quite often referred to as having once been rundown and now become rather sought-after. Seems as though according to Wiki, both had a high density population which has become less dense and therefore more desirable.
London is a bit fickle like that. 
I don’t think Hoboken, NJ, ever hit the ghetto level. I live in Hoboken now, and I think that it was always a very blue collar town with lots of industry and shipyards along the river. The gentrification did begin in the 1980s, but it was more from blue collar town to yuppie town.
I don’t think that Hyde Park in Chicago qualifies either. I went to college at the University of Chicago, and most of Hyde Park is full of students, professors, and other university workers. Just south and west of campus are some pretty grim ghettos. If those are getting better, I’d think it is just a pretty good neighborhood expanding into the ghetto.
I’m hoping that the OP will research as appropriate and get the real story.
Hopefully the OP will punch up the title a bit, and confine it to 5-6 of the most dramatic cases - probably need rags to riches examples in a decade or less with some really wicked stories behind them (as opposed to just “well, higher income people started moving in over the decades since they needed affordable rents nearer the urban core”). I somehow I think several Asian cities will be on the list - (at the very least, this gives you an excuse for some Cracked List© Japanese robot-in-city images).
Also not sure how you’re going to work in the obligatory Cracked images such as Scanners Head explosion, guy-riding-bear, and random cleavage, but I’m sure you’ll find a way. And you’ll need to come up with a line similar to one of my favorite Cracked list captions - “For the purposes of this article, you are somewhat of an idiot”
About 20 years ago, it was a bit of a hole with no shortage of housing projects and borderline slums. About 15 years ago, redevelopment efforts got most of that pushed a couple blocks east into the Western Addition area.
There was a house for sale in the mid-80s in the Arlandria area of Alexandria, VA (just across from DC) for $35k and no takers. I used to work across the street in a very run down shopping center. We found a dead guy in our dumpster. Another time we found a crack whore servicing a customer in the same dumpster. We had to close the store (with metal bars) a couple of times, with the customers still inside, because a gang fight had broken out outside. The armored car guys used to be nervous as hell, when they came to our store. I was learning Vietnamese and Spanish rapidly.
Now the same house is on the market for $599,000. And it looks to be in worse shape than it was twenty five years ago.
There was a development of condos in that area which were selling for close to $200k in 1989-90. All the locals thought the developer was crazy. Those same condos are over the half million mark now.
Nice idea for an article. However, it is Cracked and you have to play to their style. A better title for them might be “10 Historical Shitholes that You Have to Be a Millionaire to Live in Today”.
Toronto has one of the best examples of this: Cabbagetown.
It’s name originally derives from the fact that it used to house Irish workers in such total poverty that they grew cabbages on their lawns to have enough to eat, and later it was the site of Toronto’s worst and largest slum; now, its Victorian rowhouses are fancy restored digs for urban professionals.
Ponsonby in Auckland has gone full circle: began as stately Victorian residences for the wealthy, turned into a slum for Polynesian dockworkers, and is now an archetypal hipper-than-thou inner city suburb. Being a slum for druggies, mental patients and poor immigrants preserved the vast old wooden villas, since they were easily converted into dosshouses. Although it is now largely an enclave for the wealthy white middle classes, it still retains a somewhat bohemian cachet from its loose post-war community of artists, musicians, gays and prostitutes.
Denver’s Lower Downtown neighborhood was a dangerous place full of warehouses and dive bars The Terminal) until the Colorado Rockies came into being and Coors Field was built there. Within five years, it became a very trendy spot full of bars, restaurants, and shops. There are now a number of high-rise condo developments and LoDo is a desirable place to live if you can afford it.