In the 1950's and early 1960's most mid-west states had corn picking contests. The winner would go to the national contest.
I'm not going to look up the winners, but I remember the New Idea one row winning the most contests. The Moline Uni-Harvester won a lot of the two row contests. There were several Moline two row pull type, Oliver one row pull type and two row mounted, and Ford mounted one and two row pickers that were winners.
Never see any John Deere, Case, Allis Chalmers, or Massey Harris pickers that were winners in the 50's. I don't remember any Internationals being a national winner, but they may have won a state title or two. In the 1960's Allis Chalmers came out with new mounted pickers and they won several contests,
Shelled corn was becoming popular in the 60's and Gleaner self propelled combines and the Moline Uni-Shellers were about the only winners. I don't know when they stopped the contests. I am guessing in about 1966.