Can I brag? I live in a South Jersey suburb of Philadelphia. My wife and our 9-year old son ride their bikes about a 1/2 mile or so to his school every day. In fact, it was their example that encouraged me last year to get a new commuter bike and start riding my bike to work, instead of taking the train.
(Although I admit that our 13-year-old daughter often resists riding her bike to school because her helmet "messes up" her hair.)