Ernie Harburg "Frank L. Baum was an interesting kind of maverick guy, who at one point in his life was an editor of a paper in South Dakota. And this was at the time of the Populist revolutions or revolts, or whatever you want to call it, in the Midwest, because the railroads and the eastern city banks absolutely dominated the life of the farmers, and they couldn’t get away from the debts that were accumulated from these. And Baum set out consciously to create an American fable so that the American kids didn’t have to read those German Grimm fairy stories, where they chopped off hands and things like that. You know, he didn’t like that. He wanted an American fable.

But it had this underlay of political symbolism to it that the farmer—the scarecrow was the farmer. He thought he was dumb, but he really wasn’t; he had a brain. And the tin woodman was the result—was the laborer in the factories. With one accident after another, he was totally reduced to a tin man with no heart, alright, on an assembly line. And the cowardly lion was William Jennings Bryan, who kept trying—was a big politician at that time, promising to make the world over with the gold standard, you know? And the wizard, who was a humbug type, was the Wall Street finances, and the wicked witch was probably the railroads, but I’m not sure." https://www.democracynow.org/2018/12/25/a_tribute_to_blacklisted_lyricist_yip (The interview was conducted in 1996)