My apartment building on Manhattan’s Upper West Side is of the standard prewar varietal, with the faint chicken-soup-in-the-stairwell smell familiar to any New Yorker and an elevator that goes up to fourteen. And by fourteen, I mean, of course, thirteen. In this respect it is standard too; the elevator, made by Otis (I paused to double-check as I was writing this), indulges our collective superstition and forces those on the top floor to live a peculiar quotidian fiction.

In taller buildings, of course, everyone above twelve is technically living a lie, albeit of the white sort. This is a bit of magical thinking that never fails to delight me on even the darkest day. (By contrast, I have a friend who hates the convention—but then, he is of a scientific turn of mind, stubbornly logical, and generally carries on like the arrogant protagonist of a paranormal thriller who insists on moving into the obviously haunted house and ends up having all his convictions challenged, his eyes opened, and his past emotional turmoil exposed into the bargain.)

Fear of the number thirteen is called triskaidekaphobia. The negative connotations, while obscure, are thought by some to date to Norse mythology, specifically a banquet in which Loki, the thirteenth and uninvited guest, killed Balder with a misteltoe-tipped arrow. Later, Judas Iscariot helped the cause not at all by arriving thirteenth to the proverbial party. Whatever the origins, the superstition is common: French homes are rarely numbered thirteen; hotels rarely contain rooms by that number. And in Ontario, meanwhile, there are no highway thirteens.

In New York, the prohibition against thirteenth floors was initially an aesthetic one; critics warned that any building over 125 feet would cast unsightly shadows. This is clearly an objection that builders managed to overcome, but the floor took years to gain a foothold in otherwise hard-headed Manhattan. Conspiracy theorists have all sorts of ideas as to why—sinister government agencies seem to loom large—but good old-fashioned supersition is the more likely explanation.

Estimates vary widely as to the percentage of of American buildings containing labeled thirteenth floors—I found everything from 15 percent to 85 percent, with Internet sages citing vague “internal reports” from elevator companies—but it’s clearly a convention that prevails in old buildings and hotels at the very least.  In such cases, some vary the formula by calling it 12B, or, occasionally, “M,” the thirteenth letter of the Roman alphabet and not, to my eyes, less sinister. Enterprising managers might turn thirteen to a practical use; a mechanical floor, say (Trump goes in for this method, reportedly) or an unnumbered restaurant level. The custom is at this point entrenched and some developers still seem unwilling to gamble on tenants’ rationality—even if fire departments complain that the system makes for confusion, inefficiency, and potential safety hazards.

Having become fixated on this phenomenon, I took it upon myself to watch the 1999 sci-fi film The Thirteenth Floor(27 percent on Rotten Tomatoes), and was dismayed to find that it dealt with alternate realities and computer programming and had nothing whatsoever to do with architectural history. (This disappointment, it should be added, could have been allayed by means of minimal research on my part.) But no matter: it’s enough that on those days I’m too lazy to take the stairs I’m rewarded with a small mystery and with proof of our enduring irrationality. It’s supremely comforting.

Happy New Year.