Wasn't there a time not too long ago when kids walked or biked to school and only those that were 5 miles or farther were bussed in? And your father would tell you he walked 5 miles to school, in 4 feet of snow, uphill both ways without a jacket if you ever complained about walking to school?

I distinctly remember walking to school when it was close or biking if I had a bike. I suspect it's really a combination of things: ease and convenience of using a car/scooter (kids lead incredibly busy lives and are getting stressed at earlier ages); fear of child attackers (this is an issue that either is increasing or getting more press); lots of traffic to deal with (reality is with so many people turning to cars because of convenience it's harder for kids to ride to school); potential for theft of bikes (kids ain't cheap!); kids having too many places to go to after school (soccer for Janey is 10 miles away and she has 30 min to get to it while Joey is going to hockey practise in the other direction by 20 miles and has 45 minutes to get to it).

Sometimes I think all these things that make our lives more convenient actually make things worse. An interesting book I'm reading called The Obesity Myth does point out something: we are more sedentary than we were about 50 years ago (this is more likely the cause of many diseases/conditions that have been associated with obesity).

North America is a car culture and it will take gas prices that are double what they are now and no government intervention before there are changes done, IMO.