Multitudes of People! Walking up the hills!
I noticed, reading Dangerous Laughter, that Steven Millhauser tends to recombine elements over and over again in his short stories: that fabular first-person plural voice, sometimes splintering off into singular about halfway through; that archive of stock images of archetypal Americana. He has his toolkit; he applies it to the task at hand. Invariably, the task at hand has to do with describing a work or art, or, like here, of nature, that promises a new logic progressing inexorably towards an all-encompassing conclusion. Think of the Borges parable about the map the size of a country — and add another element of Millhauser's toolkit: a sense of the dread that comes while approaching the absolute, or the luminosity that comes upon reaching it.
This story, which is basically a Zen Buddhist version of The Trouble with Tribbles, is a variation on that theme, essentially timeless but actually quite timely in its atmosphere of collective expectation.
And at 1535 words, it's about two sentences too long to be a Literary Upstart submission (get your stories in!).