The music business used to spend insane amounts of money on marketing and promotion. (Of course, most of this was charged right back to the artist, but that's another story.)
The Huffington Post has a cool slideshow of the kinds of billboards that used to be seen up and down the Sunset Strip back in the 70s. These appear in a new book called Rock N' Roll Billboards of the Sunset Strip.
How times have changed.