To get a handle on this, you can read Money and Politics in the Land of Oz By Quentin P. Taylor. Below is an exerpt:
"Dorothy, the protagonist of the story, represents an individualized ideal of the American people. She is each of us at our best-kind but self-respecting, guileless but levelheaded, wholesome but plucky. She is akin to Everyman, or, in modern parlance, “the girl next door.” Dorothy lives in Kansas, where virtually everything-the treeless prairie, the sun-beaten grass, the paint-stripped house, even Aunt Em and Uncle Henry-is a dull, drab, lifeless gray. This grim depiction reflects the forlorn condition of Kansas in the late 1880s and early 1890s, when a combination of scorching droughts, severe winters, and an invasion of grasshoppers reduced the prairie to an uninhabitable wasteland. The result for farmers and all who depended on agriculture for their livelihood was devastating. Many ascribed their misfortune to the natural elements, called it quits, and moved on. Others blamed the hard times on bankers, the railroads, and various middlemen who seemed to profit at the farmers’ expense. Angry victims of the Kansas calamity also took aim at the politicians, who often appeared indifferent to their plight. Around these economic and political grievances, the Populist movement coalesced.
In the late 1880s and early 1890s, Populism spread rapidly throughout the Midwest and into the South, but Kansas was always the site of its most popular and radical elements. In 1890, Populist candidates began winning seats in state legislatures and Congress, and two years later Populists in Kansas gained control of the lower house of the state assembly, elected a Populist governor, and sent a Populist to the U.S. Senate. The twister that carries Dorothy to Oz symbolizes the Populist cyclone that swept across Kansas in the early 1890s. Baum was not the first to use the metaphor. Mary E. Lease, a fire-breathing Populist orator, was often referred to as the “Kansas Cyclone,” and the free-silver movement was often likened to a political whirlwind that had taken the nation by storm. Although Dorothy does not stand for Lease, Baum did give her (in the stage version) the last name “Gale”-a further pun on the cyclone metaphor.
The name of Dorothy’s canine companion, Toto, is also a pun, a play on teetotaler. Prohibitionists were among the Populists’ most faithful allies, and the Populist hope William Jennings Bryan was himself a “dry.” As Dorothy embarks on the Yellow Brick Road, Toto trots “soberly” behind her, just as the Prohibitionists soberly followed the Populists.
When Dorothy’s twister-tossed house comes to rest in Oz, it lands squarely on the wicked Witch of the East, killing her instantly. The startled girl emerges from the abode to find herself in a strange land of remarkable beauty, whose inhabitants, the diminutive Munchkins, rejoice at the death of the Witch. The Witch represents eastern financial-industrial interests and their gold-standard political allies, the main targets of Populist venom. Midwestern farmers often blamed their woes on the nefarious practices of Wall Street bankers and the captains of industry, whom they believed were engaged in a conspiracy to “enslave” the “little people,” just as the Witch of the East had enslaved the Munchkins. Populists viewed establishment politicians, including presidents, as helpless pawns or willing accomplices. Had not President Cleveland bowed to eastern bankers by repealing the Silver Purchase Act in 1893, thus further restricting much-needed credit? Had not McKinley (prompted by the wealthy industrialist Mark Hanna) made the gold standard the centerpiece of his campaign against Bryan and free silver?"
But not everyone agrees with this. Economist Bradley Hansen wrote an article titled The Fable of the Allegory: The Wizard of Oz in Economics in the Journal of Economic Education in 2002. Here is his conclusion:
"Rockoff noted that the empirical evidence that Baum wrote The Wonderful Wizard of Oz as an allegory was slim, but he compared an allegorical interpretation to a model and suggested that “economists should not have any difficulty accepting, at least provisionally, an elegant but controversial model” (Rockoff 1990, 757). He was right—we did not have any difficulty accepting it. Despite Rockoff’s warning, we appear to have accepted the story wholeheartedly rather than provisionally, simply because of its elegance. It is as difficult to prove that The Wonderful Wizard of Oz was not a monetary allegory as it is to prove that it was. In the end, we will never know for certain what Baum was thinking when he wrote the book. I suggest that the vast majority of the evidence weighs heavily against the allegorical interpretation. It should be remembered that no record exists that Baum ever acknowledged any political meanings in the story and that no one even suggested such an interpretation until the 1960s. There certainly does not seem to be sufficient evidence to overwhelm Baum’s explicit statement in the introduction of The Wonderful Wizard of Oz that his sole purpose was to entertain children and not to impress upon them some moral. The Wonderful Wizard of Oz is a great story. Telling students that the Populist movement was like The Wonderful Wizard of Oz does seem to catch their attention. It may be a useful pedagogical tool to illuminate the debate on bimetallism, but we should stop telling our students that it was written for that purpose."