Appropriate age for kids to go for a walk on their own?

I have 2 girls, 7 and 8. I live in a small neighborhood and while they have not mentioned it, I think they would be excited about the "freedom" of going for a walk around the block by themselves. I know a lot of it depends on maturity, judgement etc. but is this age appropriate? via /r/Parenting http://ift.tt/2kLDxWg