San Francisco (Three days @ 90,000+ viewers per day)
Berkeley (Five days @ 110,000+ viewers per day)
Statistic courtesy of Communist Agitprop Forbes Magazine
Los Angeles (duration unknown)
These signs are made quickly, easily and cheaply using scrap cardboard, paint and an overhead projector. I place them by driving around and determining which spots are easiest to see and most difficult to get to from the road. I can attach them to fencing within seconds using bungee cords and duct tape. By attaching them to the inside of the fencing there is no danger whatsoever of their falling into traffic.
These two signs (above and below) were placed in not-very-well-sealed overpasses over the Santa Monica and San Diego Freeways. Each has stayed up for over a month, passed by over 110,000 and 120,000 drivers per day respectively.
Novato and Larkspur, California (Three and five days+ at 80,000 drivers per day.)
For more information go to Freewayblogger.com