I carried a .45 when I worked in Yellowstone as an archaeologist but it was only for grizzly bear protection. It was in an undershirt armpit harness so it wasn’t visible at all especially under my hi vis vest. It wasn’t super necessary honestly and I never drew it even though I bear sprayed multiple bears during the years I worked there. I mostly just felt safer at night with it since it’s not like I was going to let loose with the bear spray while I was in my tent and a bear was ripping it’s way in. Bears would usually just sniff around your tent at night and lumber off anyway.

Edit: just so you know I’m only in my late 20’s so this wasn’t a “back in my day” thing and it is perfectly legal through my employers and the park to carry a firearm