My house in Colorado was at nearly a 9000 foot elevation (1.7 miles high IIRC) about 25 miles up in the mountains from Boulder. It was a day hike round trip to the timberline where the oxygen was so thin trees couldn’t grow. The school I attended was a K-12 and total school enrollment including all the faculty was 250 people, my graduating class would have been about 15 kids. Grades 9 through 12 total could just barely field a single football team with no backup quarterback and only a couple of B string players. Lived there about 5 years.
We moved from there to San Jose while I was in high school. Talk about culture shock! Our school there had a graduating class about twice the size of the entire K thru 12 school I attended in Colorado.