When my brother and I were young, my mom would take us on Transportation Days.

It goes like this: You can't take any mode of transportation more than once. We would start from home, walking the two blocks to the commuter rail station. We'd take the train into Center City (Philadelphians' name for "downtown"), then a bus, switching to the subway-surface--the Southeastern Pennsylvanian Transportation Authority (SEPTA)'s name for a trolley), then maybe a taxi. We always considered taking a horse-and-buggy in the historic district (Society Hill or the Independence Mall area) but we didn't like the way the horses were treated, so we never did.

At the end of the day, we took the subway to our closest station, where her friend was waiting to give us a ride home - our first car ride of the day.

My mom was never a big bicyclist, but if I have kids, a bike ride will definitely be part of our Transportation Days.

The brilliance of Transportation Days is not only that she taught us how to get around. It's that her instincts were multimodal. She understood that car dependency was a failure of the imagination and, most likely, a failure of confidence--the product of a childhood not spent navigating subway tunnels.

Once you learn the route map and step with assurance over the gap between the train and the platform, nothing is scary anymore. New cities are just light-rail lines to be explored. And your personal car, if you have one, becomes just one more tool in the toolbox--and more often than not an inadequate one, limiting both your mobility and your wallet.