The most gold in private hands is also in the USA.

#1!!! by a long shot “United States”

8,133.5 78.3%
The United States holds the largest gold reserve in the world. With 8,133.5 tonnes, U.S. gold holdings are worth approximately $269.67 billion. This massive gold reserve represents about .9436 an ounce for every person living in the country.
The majority of the American gold is reported to be held in the world-famous United States Bullion Depository in Fort Knox, Kentucky, although there is some controversy that suggests otherwise. The remainder of the U.S. reserves are held at the Philadelphia Mint, the Denver Mint, the West Point Bullion Depository, and the San Francisco Assay Office.
The top ten largest owners of gold in the world are reported to control a total of 24,258.3 tonnes, or over 855 million ounces. At current spot prices, this gold would be worth approximately $804.35 billion and represents about 15.4% of all the gold ever mined.
We continue to urge all Gold World readers to buy and hold both gold and silver in anticipation of significantly higher precious metal prices.