Eventually, currency became flat money backed only by the government's decree that establishes its value. In this way, the federal reserve could maintain a money supply at adequate levels to support a growing economy.
On March 5, 1933, Roosevelt declared a national "bank holiday" and closed the nations banks. Within a matter of days the sound banks began to reopen. The "bank holiday" was a desperate last resort to restore trust in the nation's financial system.
The FDIC promotes its trust by insuring banks and thrift institutions for at least $250,000; by monitoring and addressing risks to the deposit insurance funds.