The Long and Large Decline in U.S. Output Volatility

The last two U.S. expansions have been unusually long. One view is that this is the result of luck, of an absence of major adverse shocks over the last twenty years. We argue that more is at work, namely a large underlying decline in output volatility. This decline is not a recent development, but rather a steady one, starting in the 1950s, interrupted in the 1970s and eeirly 1980s, with a return to trend in the late 1980s and the 1990s. The standard deviation of quarterly output growth has declined by a factor of 3 over the period. This is more than enough to account for the increased length of expansions.