Here are some factors that can affect the value of a 1920 US quarter:
* Condition: The condition of a coin is one of the most important factors in determining its value. Coins that are in good condition, with few or no scratches or other marks, are worth more than coins that are in poor condition.
* Rarity: Some 1920 US quarters are rarer than others. For example, the 1920-S quarter, which was minted in San Francisco, is rarer than the 1920-P quarter, which was minted in Philadelphia. Rarer coins are worth more than common coins.
* Mint errors: Mint errors are mistakes that occur during the minting process. These errors can range from small flaws to major deformities. Some mint errors are rare and can add significant value to a coin.
* Special markings: Some 1920 US quarters have special markings, such as mint marks or privy marks. These markings can indicate the mint where the coin was minted or commemorate a special event. Coins with special markings can be worth more than coins without them.
If you have a 1920 US quarter, it is a good idea to have it appraised by a professional coin dealer to determine its exact value.