In an effort to curb the proliferation of unsightly roadside advertising, Michigan stopped issuing new highway billboard permits in 2007. Some states (Alaska, Hawaii, Maine, and Vermont) have banned billboards entirely, and the city of Sao Paulo, Brazil, has gone so far as to ban outdoor advertising of any kind.
All of that is less interesting than the fact that recently Sao Paulo has started allowing very limited outdoor advertising again, but in a way that supports the public good. In particular, 32 LED panels will be allowed near highway bridges near the city, but in return each advertiser is responsible for maintaining the bridge near that sign.
It's an intriguing, if not entirely new, idea -- private "sponsorship" of public property. What perspectives might be relevant to this idea, and what questions does it raise for you?