The top reserve currency is generally selected by the banking community for the strength and stability of the economy in which it is used. Thus, as a currency becomes less stable, or its economy becomes less dominant, bankers may over time abandon it for a currency issued by a larger or more stable economy. This can take a relatively long time, as recognition is important in determining a reserve currency. For example, it took many years after the United States overtook the United Kingdom as the world 's largest economy before the dollar overtook the pound sterling as the dominant global reserve currency. In 1944, when the US dollar was chosen as the world reference currency at Bretton Woods, it was only the second currency in global reserves.
when did the dollar become the reserve currency
1944