The time period from 1970 to 1979 saw continued evolution of the popular United States Mint Proof Sets. The decade contained a small composition change, the inclusion of a new denomination, a coinage redesign for the bicentennial, which included a revival of silver clad composition, and significant packaging changes.
The 1970 Proof Set began the decade and marked the final 40% silver Kennedy Half Dollar, until the brief revival of the silver clad composition for in 1976. This set and the following two years came in the familiar packaging last redesigned in 1968.
A major change would occur with the 1973 Proof Set. Even though the Eisenhower Dollar coin had been introduced in 1971, it had not been included as part of the regularly issued US Proof Sets. Proof versions of the dollar coins had been sold separately for 1971 and 1972. The inclusion of another coin necessitated the redesign of the package.
Instead of having the coins sealed between two plastic lenses, the coins were sealed within individual plastic rings between plastic lenses. This was further placed within a rigid black holder that opened and closed to view the obverse of the coins. This packaging is very difficult to open and contained red velvet that over time left red dust on the coins. The velvet insert was later changed to red paper to avoid this.
In 1976, the dollar, half dollar, and quarter were all redesigned with new reverses for the Bicentennial. The US Mint also issued a special three coin set containing 40% silver proof versions of the three coins.
To close out the decade, a newly designed dollar coin replaced the Eisenhower Dollar. The small sized Susan B. Anthony Dollar made its circulation and proof set debut in 1979. This year also produced two different types of mint marks, which are noted by collectors.