Where have all the kids gone?

This past weekend my little neighborhood in Mountain View had it's annual block party. Cheesy suburban tradition perhaps...but I happen to like cheesy suburban traditions. So there! It's a nice opportunity to meet that new couple that moved in down near the corner and share some food from the multitude of different ethnicities in the neighborhood. 

What strikes me every year though is the sheer number of kids on our block that I NEVER see other than at this annual party. I occasionally will see them piling in or out of the back of a car, and there are a couple of Middle-School aged kids that I see in the mornings riding their bikes to school but that's it. I'm about 1/2 inclined to put up a flyer stating that I have a ball and glove in case some kids wants to play catch or leave a cinder block and hunk of plywood in the street just to see if there is a kid left that knows what to do with it (you build a jump for your bike).

My street, 4pm on Saturday.

We don't live in a shady neighborhood. Quite to the contrary. In fact, the last incidence of property crime (in which a couple of bikes were stolen from a garage...that was left open) was over seven years ago and the Mountain View PD has no record of any sort of violent crime within a mile of us for the last ten years. The traffic levels aren't outrageous, below average in my opinion for a residential street and yet...you NEVER see kids outside playing. Nobody out playing catch. Nobody out riding their bikes. Nobody out shooting hoops. Nobody climbing trees, catching bugs, skinning their knees or generally acting like kids. 

What's changed? Why don't kids play outside anymore? Why don't parents let them, or make them?