Questions about freeway blogging arose in a recent conversation - legality, blah blah blah, after thinking for awhile, I imagined a pretty safe, effective way to "freeway blog."
One could simply fabricate a number of blank banners designed to be quickly "deployed," and then add graphics (paint, dye, whatever). Take a LARGE swath of fabric, like a sheet, hem in a 3/8 rod at top AND bottom, attach two chains with locking hooks to the top rod only. Works like this: design non-violent messages on banners, roll 'em up and hit freeway overpasses in high-traffic areas. It could be as quick as walking up, securing the banner by the hooks to fencing, and throwing the thing over the side (making sure the sign is not upside-down or backwards), move on. Even a half-hearted effort could reach hundreds of people before the sign gets removed... ?