The Zero Bound in U.S. HistoryThis figure shows U.S. short-term interest rates, specifically the interest rate on three-month Treasury bills, since 1920. As shown by the shaded area on the left, for much of the 1930s, interest rates were very close to zero, leaving little room for expansionary monetary policy. After World War II, persistent inflation generally kept rates well above zero. However, starting in late 2008, in the wake of the housing bubble bursting and the financial crisis, the interest rate on three-month Treasury bills was again virtually zero.
Source: Federal Reserve Bank of St. Louis.