The U. S. Eisenhower dollar. or Ike, was minted from 1971-1978; except none were minted in 1975. The Bicentennial Ike was double dated 1776-1976. The mint mark appears on the obverse above the date. No mint mark for Philadelphia, "D" for Denver, and "S" for San Francisco. Only the 1971-1974 and the 1976 "S" mint-marked Ikes were 40% silver (Business strikes and proofs). None of the business strikes or the proofs of the 1977-78  Ikes were silver-clad.