1949
Bretton Woods in force
In 1949 other currencies are pegged to the dollar, and the dollar is defined at $35 for official holders. Private Americans cannot redeem at the Treasury.

Bretton Woods was negotiated in 1944. Member currencies were pegged to the dollar. The dollar was defined against gold at $35 a troy ounce for official holders. That system is in force.
Ordinary Americans do not redeem paper at the Treasury. The London Gold Pool, which tries to hold the free-market price near $35, starts in 1961. It has not started.