Even though Frank L. Baum presented The Wizard of Oz as a children's story meant to entertain, many critics suggested that the story actually was a clever allegory of the Populist movement.
Dorothy's silver slippers-- represent the Populist party's desire for free silver. They wanted unlimited production of silver coins to help increase inflation, so the nation could pay off its debts.
The Tinman-- represents the Industrialized North. The fact that he no longer has a heart suggests that the northern factory workers are down-trodden and dehumanized by their long hours of work in factories.
Scarecrow--represents the simple farmers of the Populist party. Baum uses the scarecrow to make a point about the farmers he represents; he may not be the most intelligent, but he is loyal and determined.
Cowardly Lion-- William Jennings Bryan. In his campaign against Mckinley, he was portrayed as being cowardly by the media opposition because he did not support the Spanish-American War.