This question really has two parts: why is it this universe’s turn to host the All World’s Fair, and why is it being held in the city of San Francisco, at the old Mint?
It’s a matter of public record that the All Worlds Fair comes to every universe one at a time, and only once. But precisely how each new universe is selected has never been definitively established.
Here’s what former Harvard President Aleister Crowley wrote about the selection process of each new universe for the Fair, in “The Book of Universes”:
“So it is that upon the last bell that tolls upon the last hour of each Fair, announcing that this universe and all its marvels are dead to it, on that moment the first child born in another reality draws the Fairs’’eye like lightning across an empty sky, foretelling the universe and place where the Fair shall next appear.”
All Worlds Fair officials will neither confirm nor deny that this process is real, and it should be noted that several prominent scholars, including pan-universal historian Jacques Barzun, have called Crowley a fraud and a “mere occultist.” But this remains perhaps the most prominent theory.
The other widely held theory of how the All Worlds Fair selects a new universe maintains that one Traveler attending the current fair will be pulled aside by the docents, stripped naked, and forced to inhale sacred fumes from the planet Delphi. During their hallucinations they will first identify the time and manner in which the planet they sit on will die, the eventual winner of that universe’s eternal war between order and chaos, and finally the next universe and place where the All Worlds Fair will be held.
Fair officials likewise refuse to offer comment on this process.
Once Earth was selected, Vox said, San Francisco was always on the short list, but quickly came to prominence through the lobbying efforts of former mayor Willie Brown.
“Every restaurant our Board of Ministers ate in, he’d send them a bottle of wine,” she said. “Every meeting I had in a major city like London or Beijing, he’d bribed someone to speak up on your behalf. For a while it seemed like he was in league with every demon lord I contract with: they constantly brought up his name. He must have his own seat waiting on Hell’s city council.”
In the end, Vox said, San Francisco was chosen for a variety of reasons. “The City sits on a number of ley lines, which is vital. You have easy access to acrobats, which we can’t get enough of, and the pad thai is excellent. The last universe I helped set up in you couldn’t get good Thai food anywhere within three galaxies. The crew loves this.”
And using the old San Francisco Mint? “That was a stroke of genius,” said All Worlds Fair site enforcer Alexander Rex. “It’s made of concrete and steel, it’s bigger on the inside than it is on the outside, it has a limited number of entrances and exits, and someone already doused the place in Delphic gasses. I have no idea how that happened, but the space is exactly what we need.”
He added “Thank you San Francisco!”