There are two main problems with the HBA, Ashburn says. It allows billboards in “commercial and industrial areas” (often very loosely defined), which is why there’s a forest of them, for example, on sections of I-294 and on the Stevenson. It also requires compensation to billboard owners for equipment and lost revenues on any signs the government wants to take down. That’s made it too expensive for most local governments to get rid of billboards once they go up. States that fail to comply get a cut in their federal highway funds.
So the HBA was relatively ineffective, Ashburn says, except for one safety-inspired prohibition, written into most of the state-federal agreements required by the act, that forbade “intermittent, flashing, or moving lights.” Since billboard ads were made of paper glued to board, nobody cared much about that. Until the digital revolution.
Light-emitting diodes (LEDs), the technology behind most digital billboards, were invented half a century ago but weren’t adapted for billboards until relatively recently. In spite of high initial costs (about $250,000 for the big ones), these computer-controlled light boards offered clear advantages: they eliminate printing and labor-intensive application, and are brighter and more animated than anything else in the visual field. Measured in units called “nits,” they literally outshine the sun, creating impact that can command a higher rental dollar. And here’s the attribute that really had the industry salivating: they can be changed repeatedly, in a flash, so the same sign can be rented to numerous advertisers simultaneously.