When Armed Robbers Ruin a Brilliant Commuting Scheme

"Casual carpooling" is a relatively old and fascinating little transportation subculture that has largely been obscured by the rise of companies like Lyft and Sidecar, tech-enabled platforms that have stealthily borrowed the name of "ride-sharing." Casual carpooling, on the other hand, predates smart phones. It involves no technology. It is vastly more anonymous. And for that reason, it also much, much more interesting.

To my knowledge, major casual-carpool networks exist only in Washington, D.C., and the San Francisco Bay Area, two places where the commuting patterns and infrastructure are conducive to the central bargain involved here: You get in my car for free, and I ride faster to work in the HOV lane for free. There's no money involved, no apps to connect people, often even no names exchanged between passengers and drivers. The system works because, over time in these two metros, a quasi-formal map of pick-up and drop-off locations has emerged.