By the end of WWII the US dollar replaced the British pound as the world’s primary reserve currency and the most used currency in international transactions. Until 1971 the US dollar was backed by gold. Since 1971 the US dollar is backed by the US economy and the petrodollar system. The recent shale oil boom in the USA has strengthened the US petrodollar, but will that be enough to meet the challenge of competing with China’s planned petrocryptocurrency?