So while cars became popular in the 50s, it look a long time for us to basically build everything around them. As late as 1969, 48% of kids walked or biked to school, which declined to 13% in 2009^. This has been the result of a combination of real and perceived dangers, and subject to somewhat of a feedback loop as we've made roads wider and faster.

I was lucky to be able to walk to school as a kid in the 90s, and found that time to be a delicious moment of early freedom each day as kids from my neighborhood and I chose our route and cut through backyards and patches of woods to pick up other kids. I lived in a small town without wide or fast roads, so this was largely safe, but I understand why it's not possible in most suburbs today. I loved my ability to ride my bike to friends' houses and down to the town beach in the summer, without having to ask my parents for a ride.

I think I would have been a very unhappy kid growing up in the typical American suburb of today, shepherded between structured activities and constantly monitored by adults. Retreating to a private online world may be an unhealthy coping mechanism, but it makes sense.

^ http://guide.saferoutesinfo.org/introduction/the_decline_of_...