Based on an analysis of United States coinage, the presence of silver is primarily determined by the year of mintage and the denomination of the coin. A general principle is that dimes, quarters, and half dollars intended for circulation that were minted in 1964 or earlier are composed of 90% silver.
Specific silver dollar series include the Morgan Dollar, minted from 1878 to 1904 and again in 1921, and the Peace Dollar, minted from 1921 to 1928 and from 1934 to 1935, both of which contain 90% silver. Half dollars with 90% silver content include the Walking Liberty series (1916-1947), the Franklin series (1948-1963), and the 1964 Kennedy half dollar. Likewise, Washington quarters from 1932 to 1964 and Standing Liberty quarters from 1916 to 1930 are also 90% silver. For dimes, the Roosevelt series from 1946 to 1964 and the Mercury series from 1916 to 1945 share this 90% silver composition.
There are also coins with lower silver content. From 1965 to 1970, Kennedy half dollars were produced with a 40% silver composition. Certain uncirculated and proof Eisenhower dollars minted between 1971 and 1976 also contain 40% silver. An exception to the standard coin compositions occurred during World War II, when Jefferson nickels minted from 1942 to 1945 were made with 35% silver. These "War Nickels" can be identified by a large mint mark (P, D, or S) located above the Monticello image on the reverse side.
