Probably depends on the area and other factors... in my area it was totally normal for kids to walk some half a mile to a mile home in middle school just over a decade ago and I don't think it's changed. I think even elementary school was normal with possibly a smaller distance (not sure how far kids went, but a couple blocks was fine).
Twenty five years ago in my area, a mile to half a mile was routine for elementary school students. By middle school, I would come home to an empty house and go pick up my brother who was in kindergarten. Nowadays, my daughter is in elementary school and I see parents drive their cars up to the bus stop and hover until the bus comes.
The majority of me thinks that parents today need to relax because the chance of your kid being kidnapped or whatever are about the lowest they've ever been. And then another part of me wonders if that's BECAUSE today's parents are paranoid.
