According to the New York Times (4/7/2014):
[T]his summer, images by dozens of famous American artists will be plastered on 50,000 displays from electronic billboards to bus shelters, an initiative by leading museums and the billboard industry to create one of the largest outdoor art exhibitions seen in the country.
Museum directors hope the project, called Art Everywhere, will draw more visitors to their galleries. One of the five museums included in the project is the Art Institute of Chicago.
Beginning on Monday and running through May 7, the public can view the 100 selections at ArtEverywhereUS.org and vote for favorites. The 50 images that receive the most votes will be announced on June 20 and be reproduced on outdoor displays coast to coast in August.