Billboards are large advertising signs, often placed along roadways and other areas of high traffic and exposure. In 1965, in an attempt to preserve the scenic beauty of America's highways, Congress passed the Highway Beautification Act (HBA). Its aim was to prohibit construction of new billboards on scenic and rural federal-aid highways, and to require the removal of illegal billboards (those erected without proper permits). However, due to loopgoles and amendments, the Act hasn't been effective in reducing billboards. Local areas also regulate billboards placed within its jurisdiction.
Billboards in space have recently become controversial. According to the Federal Aviation Administration (FAA), outsized billboards deployed by a space company into low Earth orbit could appear as large as the moon and be seen without a telescope. The FAA proposed in May 2005 to amend its regulations to ensure that it can enforce a law that prohibits "obtrusive" advertising in zero gravity.
(Source: http://www.cnn.com/2005/TECH/space/05/20/space.advertising.reut/index.html)
