The composition of US coins has changed over time, as follows: •

• Before 1964: US dimes, quarters, half dollars, and dollars were made of 90% silver.
• 1965-1970: Kennedy half dollars were made of a mostly silver outer layer and a mostly copper inner layer, for a total of 40% silver.
• 1971-present: Kennedy half dollars are made of a copper-nickel alloy and contain no silver.