Dorothy is said to represent the American people and their values.
The character Scarecrow represents western farmers. Their years of failed crops created self doubt and insecurities about intelligence, just like the scarecrow.
The Tin Man represented industrial workers. They experienced dehumanization. He was rusty, and immobile which is how some people felt after they lost their jobs because of factories closing.
The Cowardly Lion represented William Jennings Bryan. He was a politician in the late 1800s and supported the free silver movement. He is similar to the cowardly lion because he was viewed as having all roar, no bite.
The Yellow Brick Road represented the gold standard. The yellow brick road lead to power. Power in America meant you had money, so if you had gold.
The Silver Slippers represented the Free Silver Movement. Which was the political issue of farmers wanting the dollars value to have fixed ratios for gold and silver.
The Wicked Witch of the East represented eastern business, eastern financial industrial interests, and gold standard allies.
The Flying Monkeys represented Native Americans. They reference the government reservation policy, when the monkey king says " We were a free people , living happily in the great forrest flying from tree to tree, eating nuts and fruit, and doing just as we pleased without calling anyone master."
The Cyclone represented the free Silver movement, and political upheaval. As the farmers suffered from deflation, some had there farms ripped away from them, like the cyclone did to Dorothy's families farm.
The Wicked Witch of the West represented William McKinley who defeated William Jennings Bryan, during the time of the free Silver movement. I also believe she represented the American government in the way she bossed the flying monkeys around, who represented the native Americans.
The Good Witch Glenda of the North represented northern workers and political issues.
Emerald city represented Washington D.C.
The Munchkins represented the common American people, but they are also said to represent the issues involving child labor.