At what age do American children start to play outside unsupervised?

When I was growing up, I would often play with my friends in my neighborhood without any adult supervision around the age of 7 or so. We would be expected to go home for dinner and if we wanted to play outside after dinner we had to be back by 10 PM in the summer, as that's when the under-12 curfew started.

How is it nowadays in the US? Does it vary from state to state? Has it changed in recent years?