Dorothy represents the westerners as they had another viable currency for the people all along, silver.
The Scarecrow represents American Farmers during the late 19th century as well as many of their problems.
The Tin Man represents American industrial workers, the steel industry workers, especially.
The Cowardly Lion represents a metaphor for William Jennings Bryan, as he had a pacifist standing on World War I, hinting at cowardice.
The Winged Monkeys represent the indigenous peoples of the Great American plains as The King of the Winged Monkeys tells Dorothy, "Once we were a free people, living happily in the great forest, flying from tree to tree, eating nuts and fruit and doing just as we pleased without calling anybody master. […] This was many years ago, long before Oz came out of the clouds to rule over this land."
The Wizard of Oz represents scheming politicians that use gadgets and tricks into believing he is wise and powerful, when he is actually evil and selfish.
The Yellow Brick Road represents the gold standard
The cyclone represents the political upheaval of the 1900's, as the cyclone turned a bleak land into a world of color and prosperity.
The Emerald City represents the fraudulent world of greenback paper money that only pretends to have value.
The Wicked Witch of the West represents the American West, which would explain why the Flying Monkeys are the indigenous peoples of the American West
Glinda the Good Witch represents a power hungry mongrel as she used an innocent young girl to over-throw her sister and the wizard so that she could control all of Oz.
Some say that Toto represents prohibitionist trotting soberly behind populists, if Dorothy were to represent populists.