Editor's note: This is an excerpt of Planet Money 's newsletter. You can sign up here . US Federal Reserve Chairman Jerome Powell ANDREW CABALLERO-REYNOLDS / AFP via Getty Images As the global economy shuts down, the U.S. Federal Reserve has begun sending billions of dollars to central banks all over the world. Last month, it opened up 14 " swap lines " to nations such as Australia, Japan, Mexico, and Norway. A "swap line" is like an emergency pipeline of dollars to countries that need them. The dollars are "swapped," i.e., traded for the other country's currency. The Fed has also started allowing around 170 foreign central banks that hold U.S. Treasury bonds to temporarily exchange them for dollars. Sending billions of dollars abroad in the middle of a historic economic crisis might seem crazy: As America's economy crumbles, why are we moving our precious dollars *out* of the country? The answer has to do with the Fed's unique position in the global economy. Dollars are the lynchpin