From the NYTimes article:
Last Thursday, Michigan lawmakers held hearings on legislation, the first of its kind, that would impose a two-year moratorium on the construction of new billboards. Minnesota’s legislature is scheduled to hold hearings this month on a similar moratorium...There's 119 comments at the time of this post.
The Federal Highway Administration has been conducting a study, which it says will be completed this summer, that uses eye-trackers inside cars to see whether drivers who have volunteered for the study look at the digital billboards, and for how long. The agency also has organized a tour this spring to take researchers to various cities around the world to study how other nations are regulating digital billboards.