Where have all the kids gone?

It's been uncharacteristically warm here in Colorado....very un-February and un-March like I must say! Cruising down our neighborhood street on intermittent 60-70 degree days when our two boys were young was like finding yourself inside "The Family Circus" comic strip. The road and walks were lined with kids of varying shapes and sizes on trikes, bikes, hot wheels, roller blades and skate boards once school let- out for the day. Driveways with basketball nets were teeming with middle-schoolers, and dogs and cats ran free!
The day before yesterday temperatures soared into the 70 degree range here in Parker, yet fewer than a few children were outside post-school. After school activities acount for much of the disappearance of neighborhood play, but whatever happened to bike-riding, street hockey, driveway basketball, kick-the-can, and jump roping?
Obesity in children is at an all-time high in the U.S. It doesn't take an Einstein to figure out why.... No longer do kids RUN home to " play outside," but instead plop down in front of their PC, Play Station 2, or favorite HD DVD movie! The statistics aren't good...the life expectancy over the next few decades could decline unless aggressive efforts are made.
Where have all the kids gone? Whatever happened to the imaginative play of childhood?