In Washington, D.C. casual carpool
ing is called slugging. There are “drivers” and there are “slugs”. One needs extra occupants to use the High Occupancy Vehicle
(HOV) lanes and the other needs a ride. This process is now highly formalized, but still unregulated, with the Washington Post
publishing slug line sites, lost and found web pages and slugging etiquette
(don’t cut in line, be courteous, do not offer or accept money)..
In D.C. the original and the most famous slug line is based at the Pentagon. Slugging has always been felt to be a safe activity because the participants are mostly professional government employees. I’m not quite sure of the logic here, but that’s the way it is viewed.
The “system” has since expanded to include many locations throughout the city and into Virginia.