Because it's October
Here's the thing about "haunted houses."
The genre (gothic) started with The Castle of Otranto. But its real boost came from Edgar Allan Poe, who passed it on to H.P. Lovecraft who passed it on to Shirley Jackson.
Noticing a pattern, here? Or at least the origin: 19th century, no earlier. And even Poe had to set most of his "haunted" stories in places where European habitation was far older than it was in America. The reference to the tarn in "The Fall of the House of Usher" is the giveaway; the term is Scottish, and it refers to a Highland lake. "The Cask of Amontillado" takes place in Italy during Epiphany (a celebration largely unknown in Protestant America, outside Catholic southern Louisiana). Most of Poe's stories set in "spooky" places are set in places where "the weight of the lives that had been lived in these places" can be felt.
There weren't many such places in America in the mid-19th century. There still aren't.
I felt that weight when I first set foot on European soil, 40 years ago this year. It was immediately apparent to my senses if not my rational mind (I couldn't point to any one factor to explain it, especially since the first soil I stepped on was the tarmac of an airport. It was not a medieval airport.) that human beings had been marking and reshaping (consider the "Netherlands") this continent for millennia, far longer and far deeper than any impact my ancestors had impressed on America.
And that sense of age, and the impression that it matters, is purely Romantic; as are gothic tales, and stories of "haunted houses." We haunt them, not ghosts. And by "we" I mean we post-Romantic Europeans and Americans.
It was that weight the Romantics felt as they saw everything being plowed under, or abandoned, for the factory and the machine. Once again European culture turned to the Greeks and the Romans of yore, but this time they also turned to European culture: folk tales were preserved by the Brothers Grimm, and soon witches became part of literary culture. Ghosts, too; and then vampires by the end of the 19th century, and soon we were reveling in invented folklore because the real thing wasn't interesting enough, so that "even a man who says his prayers, and whose heart is pure and light, can become a wolf who the wolfbane blooms, and the moon is full and bright." It's not exactly the Green Lantern pledge, but it might as well be. It is that weight of loss, of abandonment, that made us look back and grab with both hands and pull forward all that fear and terror, and when it wasn't so fearsome and terrible (we quickly bowdlerized the Brothers Grimm, then set about inventing new stories, so great was our hunger for them) enough, we turned to Lovecraft and then modern horror. We didn't do this because of the Renaissance, nor because of the Enlightenment; we did it because of the machine.
O machine, O machine!
So terror resided in the old, as it haunted the new. Castles, ruins, old houses; blighted landscapes were still signs of plague (the Wasteland around Grail Castle becomes the withered landscape outside the House of Usher) but became scarier, so that Irving's rather benign (though excellent) story of Ichabod Crane becomes a nightmare hellscape of black leafless trees against a moonlit sky, and the pumpkin becomes a leering jack o'lantern that leaves a trail of flame in the sky as it hurtles away from the demonic horseman. Owls become, not creatures a man like Crane would be familiar with at night, but a leering face of danger. Bats fly from nowhere, because they are symbols of evil and vampires. It isn't Irving's audience Walt Disney was trying to scare, but us: city dwellers who've never heard an owl or seen a bat fly (they tend to fly alone, and are very, very small, not huge and menacing and flying in masses). And it all extends the gothic elements from a century before. In ghost stories, if it ain't gothic, it ain't shit.
It's not that I don't believe in hauntings. I've known friends with weird and inexplicable tales, and my mother and her twin were connected in a way that can only be described as ESP (although it didn't affect my mother when her twin died, so....). When a group came to photograph spirits at the graveyard of the church where I was pastor (just outside the front door of the parsonage, and 150 years old; old for this part of Texas, for Europeans here, anyway), I joined them. I explained that I believe in the Father, the Son, and the Holy Ghost, so why not spirits?
But I know where tales of haunted houses come from, and you don't find them in the literature before the 19th century. You can find tales that sound like haunted house stories, but they bear faint, if any, resemblance to Hill House or the House of Usher (or the castle of Otranto). No, that fascination with eldritch places, with ruined abbeys (the London haunt of Dracula) comes later. Even Frankenstein doesn't bring his Creature to life in a castle in a thunderstorm (two elements of gothic; you could look it up), but in a student's room, muttering occult alchemical phrases and doing undescribed things (the blinkenlights and spitzensparken of the movies, and even "Penny Dreadful," bear no relation to the book). There's a reason for that; it's the same reason Dracula lives in a castle, and takes refuge in an abandoned abbey in modern-day (for Stoker) London. By the end of the 19th century, Stoker's audience was well educated in gothic; they knew what to expect, and they knew what they wanted. If it ain't gothic, it ain't shit.
But it also ain't universal. What we think of as a "haunted house" has to be changed dramatically to be found in any other culture; just as what we think of as a "witch" in this month of Hallowe'en bears no resemblance to even the "witch" of Endor, or even the alleged "witches" of Salem, Massachusetts.