Is it Sierra or Sierras?

https://www.sfgate.com/travel/article/Sierra-vs-Sierras-Nevada-California-mountains-16325112.php

“We humans are strange creatures, right? These battles over language may have roots in some tribal identity creation past, or provincial superiority complexes, or just pride of place,” he added. “Who knows.”

All I know is what at first seemed like curmudgeonly nitpicking ultimately feels like something else. These readers point to linguistic propriety as the reason they’re distressed by that ‘s’ on Sierra. And maybe I should take them at their word. But ultimately, I don’t think those emails were about grammar at all. They were, I now believe, about loving a place so much that you want to claim it as your own.”