AP Success - AP US History: Bank Panics of 1930 to 1933

When a bank needed cash, because its customers were panicking and withdrawing funds en masse, the bank had to turn to its correspondent, which might be faced with requests from many banks simultaneously or might be beset by depositor runs itself. The correspondent bank also might not have the funds on hand because its reserves consisted of checks in the mail, rather than cash in its vault. If so, the correspondent would, in turn, have to request reserves from another correspondent bank…

The [bank panics caused] deflation because they convinced bankers to accumulate reserves and the public to hoard cash…Together, hoarding and accumulating reduced the supply of money…As the stock of money declined, the prices of goods necessarily followed.

Deflation harmed the economy in many ways. Deflation forced banks, firms, and debtors into bankruptcy; distorted economic decision-making; reduced consumption; and increased unemployment.