Lionel introduced the 310 billboard set in 1950. The set came with 5 plastic frames and some cardboard billboards. Most years the billboards changed.
The billboards were also included in Lionel Sets. I’ll add pictures of billboard sheets from different years in the future.
The earliest versions of the 310 billboard sets were sold in the classic orange and blue Lionel boxes. The last versions of the billboard set came on a blister car as shown above. The blister card is worth more than the set of billboards even in poor condition like the one above.
Lionel also made a 410 billboard blinker to go with the 310 set.