Back then - no legal minimum, no unemployment insurance either.

So you would expect the lowest paid to have been even lower back then. And I wish I could find the studies to see what the number were actually based on. But even if we're comparing CEOs of industry to farm workers, let's say the lowest-paid assembly line workers are making $15/hour. Farm workers would have to be making $1.50/hour for that to account for the whole difference in the ratio.