There are problems left over from history. After World War II, the Bretton Woods system was established. The Bretton Woods system was a financial exchange standard based on the US dollar and gold.

Its essence is to establish an international monetary system centered on the U.S. dollar. Its basic contents include pegging the U.S. dollar to gold, pegging other countries' currencies to the U.S. dollar, and implementing a fixed exchange rate system.

The U.S. economy is strong, the currency market is open, and the political situation is stable. For governments, gold stored here gives a sense of security.

After the Bretton Woods system came to an end in 1973, countries could no longer freely exchange gold from the United States and ship it back home.

There are two major gold vaults in the United States, one is the New York Reserve Bank vault in a rock formation 24 meters deep under Manhattan, New York, and the other is the Fort Knox military camp in Kentucky.

Most of the gold reserves of other countries in the world are in Manhattan, New York, and the Federal Reserve's gold is in the Fort Knox military camp.