Here are some of the factors that can affect the value of a 1901 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 blemishes, are worth more than coins that are in poor condition.
* Rarity: Some varieties of the 1901 quarter are rarer than others. For example, the 1901-S quarter, which was minted in San Francisco, is rarer than the 1901-P quarter, which was minted in Philadelphia. Rare coins are worth more than common coins.
* Grade: Coins that have been graded by a professional coin grading service are worth more than coins that have not been graded. Grading services assign a grade to a coin based on its condition and rarity. Coins that are graded higher are worth more than coins that are graded lower.
If you have a 1901 US quarter, you can take it to a coin dealer or a professional coin grading service to get an accurate estimate of its value.