It varies by population density. Where i grew up, a small town surrounded by many rural and semi-rural areas, the nearest high school to mine was about 20mi awa

It varies by population density. Where i grew up, a small town surrounded by many rural and semi-rural areas, the nearest high school to mine was about 20mi away, and most attendees did not live in reasonable walking distance to any high school. So you had to drive, be driven, or take the school bus. Where I live now, a very rural area, there are only two high schools in a 100 mile radius.