For all the talk of America’s decline, the United States offers the world one product that no country seems able to replicate ? universally accepted money. If a multinational needs cash to drill for oil in Nigeria or rich Indians want to import BMWs, the dollar is often the currency contracted for payment.

Central banks around the world must hold major foreign currencies ? dollars, euros, yen and so forth ? to back up their fiat money.

As New York offers a deep, sophisticated and reliable capital market, and traders can buy virtually anything in America, central banks must hold dollars above all other major currencies to be taken seriously by private investors.

The dollar accounts for 63 percent of central bank holdings, followed by the euro at 20, even though the U.S. economy is smaller than Euroland.

The dollar has gained an outsized role for the same reason English is increasingly the global language. In trade as on the internet, it is easier to have a common denominator ? America’s currency and mother tongue.

Overall, about 40 percent of imports worldwide are invoiced in dollars even though the United States accounts for only about one-tenth of global sales.

Foreign multinationals and trading houses store hordes of dollars to conduct business and hedge risk. Foreign banks take dollar deposits, pay interest on those in dollars and offer dollar loans. Foreign governments and businesses issue dollar-denominated bonds and virtually all of this is electronic, much of it unregulated and most importantly, the result of private-sector choice.

The fact is no other currency has the global utility and supporting infrastructure of the greenback.