Strollerderby

I'd say five is the norm on my city block.  The occasional little sibling tags along, but typically a parent is within earshot when the little ones are out.  If the kids are running beyond our yard, I tell them to stick together and to return to our yard when the football game (or whatever) is done and/or if the other kids all have to go inside for some reason.  I have based my decision on the ability of my children to exercise impulse control (i.e. not running out into the middle of the street) and their ability to recite and comprehend basic safety points to me (that have been drummed in their dear little heads since birth.)

It's an interesting question for city-dwellers who live in apartments - other than in the next room (where we can hear everything) - our kids don't have much of an opportunity TO play unsupervised, until they're old enough to go to the park themselves (I'd bet most people would say older than 5 on that one, as you're guaranteed to have strangers, and might have some people on the streets with mental issues in a park, whereas I might feel OK with a 5 year old in a backyard with a window I can look out of.)

We've been letting our nearly 6 year-old play with the older, neighborhood kids outside and unsupervised with a limited range of 4 houses and she needs to let me know if she's going inside. She's an only child and rarely wants to play outside by herself. So far, so good. But we have the best backyard on the block and the older kids tend to play with our daughter to be able to play in our backyard. To some extent, that's ok. So long as they genuinely include her and include her when they're not in our backyard. But they're gradually getting less inclusive and tending to treat our backyard as the local park with our daughter playing by herself vs with them. (We don't let them go back there without us so they have to invite our daughter to be able to play there.) And we had one neighbor kid who was bringing his playdates over to play in our backyard, including our daughter just to be able to do so. I've put a stop to that.

It's a tough balance. She loves the big kids and would be crushed to find out they're playing with her so much just to play in our yard. But I also want her to stand up for herself and this is a good place to learn. So I think I'll be doing a lot of weeding in the backyard this fall so I can try and keep things more fair. And I'll be inviting kids her age to play more often.

My four-year-old plays in the front and backyards by herself. She's allowed to go as far as our property line on the sidewalk if she's riding her trike, and she doesn't go beyond those boundaries.

Maybe it's because our last neighborhood was extremely dangerous, but where we live now is a sizeable suburb, and by no means isolated, but it's a rare day when someone besides a neighbor drives down our street, and rarer still that a stranger walks by. I think people focus too much on dangers that probably don't exist, while ignoring the danger of not allowing a child to develop a sense of self-reliance and a good imagination for play.

My four-year-old plays in the front and backyards by herself. She's allowed to go as far as our property line on the sidewalk if she's riding her trike, and she doesn't go beyond those boundaries.

Maybe it's because our last neighborhood was extremely dangerous, but where we live now is a sizeable suburb, and by no means isolated, but it's a rare day when someone besides a neighbor drives down our street, and rarer still that a stranger walks by. I think people focus too much on dangers that probably don't exist, while ignoring the danger of not allowing a child to develop a sense of self-reliance and a good imagination for play.

I live on a busy street, and just had a fence and gate installed in my driveway so my 4 year old can out in the back yard by herself.  She knows she's not allowed to open the gate, and follows that rule.  Though, she still usually wants me to come play with her.

Sometimes she plays with the 7-year-old next door, but if they go out in front, I go out there.  The school-age kids all ride bikes up and down the block and don't seem to have a problem with the busy street.  

I live on an extremely busy city street.  The MTA buses barely even stop at the stop sign on the corner.  So neither of my kids will be allowed out front alone any time soon.

I started letting our son play in the back yard while I stayed indoors when he was about 3 1/2.  It's fenced on all sides and the only door entrance is padlocked, so he couldn't get out and no one could get in.  I could stay inside and sit by the window and watch him.