In December 1974, US citizens were allowed to freely trade gold bullion for the first time in 40 years. The 1974 bill, signed by President Gerald Ford, resulted in the legal trade of millions of gold coins, which were previously sent overseas during the initial 1933 trade ban. Because of this, the United States got a fresh injection of old coins and re-established a healthy and active gold market.
Read more about the Gold Reserve Act.