Here are some factors that can affect the value of a 1966 liberty half dollar:
* Mint mark: 1966 liberty half dollars were minted at three different mints: Philadelphia (no mint mark), Denver (D), and San Francisco (S). The San Francisco mint mark is the most rare, and coins with this mint mark are typically worth more than those minted at Philadelphia or Denver.
* Condition: The condition of a coin is also an important factor in determining its value. Coins that are in excellent condition, with no major scratches or blemishes, are worth more than those that are in poor condition.
* Grade: Coins can be graded on a scale from 1 to 70, with 70 being the highest grade. Coins that are graded higher are worth more than those that are graded lower.
* Rarity: Some 1966 liberty half dollars are more rare than others. For example, the 1966-D half dollar is the rarest of all 1966 half dollars, and it is worth significantly more than the other two mint marks.
If you have a 1966 liberty half dollar, you can use these factors to estimate its value. You can also take your coin to a coin dealer or appraiser to have it professionally appraised.