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Luna ruffled her wings as she thought back through the long years. "Dame Pansy's grandson Flagstaff helped organize it into an annual event. Always a sensible bunch, those Pansys. They said once a year was better than having pegasi disappear willy nilly into the wild lands of the perimeter, plus a full field of flyers meant safety in numbers from the monsters and savage beasts that still swarmed on the margins of the realm. The first official race was held maybe fifteen years after that first run along the border, and every year the route expanded as more settlements popped up."

She rolled her eyes. "More pegasi bravado there, as a new crop of flyers tried to one up last year's winners by insisting that since the race was meant to be along the borders, that included any new additions as the frontier grew."

The night princess gave Twilight a shrug. "Of course, Equestria's expanded a fair bit while I was out of the picture. You could fit at least three times the distance Sunchaser and Westwind flew into the route it follows now."

She gave a nod toward the starry design of two pegasi drifting across the night sky. "Those two glory hounds had to content themselves with being the first ever Pegathalon flyers, and take it with what passed for grace that a succession of young stratobuckers were constantly breaking their distance record. I made 'em a constellation just to get 'em to stop being such big babies about it."

https://www.fimfiction.net/story/34622/21/earth-sky/part-21-word-gets-around