I believe that sending a 9 year old onto the subway alone is not only a very stupid thing to do but quite possibly criminal in some places.
Kids can build a sense of independence and self reliance without these kind of knee jerk reactionary escapades. It just takes a bit more actual participation by and creativity from the parents.

Yep. Kids can build their sense of independence and self reliance with you right there participating and being creative for them. And letting a kid catch the subway alone (on a route he’s taken many times with you) is knee jerk and reactionary. I love how so many of the commenters on freerangekids seem to assume that her kids (or any kid who’s allowed to do stuff at an age they personally don’t think is appropriate) were coddled and protected (also known as parenting properly, depending on who you ask) all the time up to the point where they suddenly let them walk to the park or catch the train alone. That really isn’t the way it works. If you want the sort of kid who can successfully and safely catch the subway at age nine you don’t just let him do it one day and see how it turns out. It starts at the beginning with lots and lots of small decisions, lots of letting kids fall over and fail in contexts where nothing seriously wrong can happen, lots of letting them play just a little out of sight for a few minutes at a time.

In our house it started, consciously at least, with asking the kid to choose his socks every day. We thought we were quite brilliant with this, except of course, our son has absolutely no interest in socks. Couldn’t give a rats which socks, and has been persistantly removing all socks ever since he was able. Still can’t get him to show any interest in socks. He does choose shoes though, we give him two options that are ok (unless there’s some particular reason for a particular choice, in which case we make it for him and tell him why it’s a gumboots day – some days, shock horror, we take him outside when the weather is less than clement and to places without paving!).  The other essential component of teaching kids to walk, ride a bike, or catch public transport alone is to walk, ride a bike or catch public transport with them lots of times. It’s not about setting kids loose, it’s about teaching them how to cope with every day things. It’s rather scary to see how many people seem to be horrified at the idea of letting a kid of ten or eleven walk to the park alone (any park, ever, no matter how safe the neighbourhood, or how close to home it might be) but have no problem with teaching that same kid to drive at sixteen.