Three sets in the same year
 

What was the first year that three more or less nationally issued sets with distinct designs from different companies that were sold with gum/candy? I can get the argument that there were different caramel backs, or tobacco cards issued the same year, but most of those that I know of had the same fronts. I guess it was 1933 as Tattoo Orbit, Delong, and Goudey were all issued in the same year. Of course 1941 had Playball, Goudey, and Double Play. I don't think there was another year with three set until 1981. I am setting Wheaties aside.

There was also a 52 card Rittenhouse Candy set issued in 1933. If it meets your criteria then that makes 4 sets that year.

That one was totally off my radar Jay!

I would say Old Judge, Allen & Ginter and Goodwins was the earliest "Mainstream"

That sounds about right...

There were other tobacco ones too, depending what you call mainstream.

https://luckeycards.com/n284.jpg

For 1933 you can add on Butter Cream, George C. Miller and Uncle Jacks.

US Caramel is a 1933 issue as well, not 1932.

1909. E92, e95, w555.