Lobby cards have been produced and shipped to theatres for display in their lobbies since their inception in the early 'teens.
These small movie posters (usually 11”x14” in a landscape, or horizontal format, printed on card stock) were generally produced in sets of eight, although the number of cards in a set can vary from as few as four to as many as 16.
As the name suggests, these small movie posters were designed for display in a theater’s lobby or foyer with the intention of luring patrons into the theater by showing glimpses of key scenes from the movie.
However, with the decline of the traditional theatres and their replacement with multiplexes with tiny lobbies, lobby cards themselves became a thing of the past. Consequently, by 1985 most American studios stopped making them.
However, interestingly enough, these very same American studios have continued producing "American" lobby cards for distribution abroad. Some of these lobby cards find their way back to this continent because of collectors' demand. These newer cards are not priced as high as the classics, although they can be just as rare. The bottom line is that if you like to collect, say, Johnny Depp, you may find it just as difficult as collecting Clark Gable.
I used to love looking at the posters and lobby cards on display in the lobby at the theatre when I was a kid. I really don't know why the rise of multiplexes ruined that experience, because there are many multiplex lobbies that are huge and have plenty of room for lobby cards and artful poster displays.