The 50-year-old petrodollar agreement between the U.S. and Saudi Arabia was just allowed to expire. The term “petrodollar” refers to the U.S. dollar’s role as the currency used for crude oil transactions on the world market. This arrangement has its roots in the 1970s when the United States and Saudi Arabia struck a deal shortly after the U.S. went off the gold standard that would go on to have far-reaching consequences for the global economy. In the history of global finance, few agreements hav...