In September 2006, the mayor of Sao Paulo passed the so-called Clean City Law” that outlawed the use of all outdoor advertisements, including on billboards, transit, and in front of stores. Within a year, 15,000 billboards were taken down and store signs had to be shrunk so as not to violate the new law. Outdoor video screens and ads on buses were stripped. Even pamphleteering in public spaces has been made illegal. Nearly $8 million in fines were issued to cleanse Sao Paulo of the blight on its landscape. Seven years on, the world’s fourth-largest metropolis and South America’s most important city remains free of visual clutter and eye sore that plagues the majority of cities around the world.

Source: Sao Paulo: The City With No Outdoor Advertisements

Maybe we could do this in Iowa City