Depressions can last anywhere from three to seven years

Depressions are basically long recessions - they can last anywhere from three to seven years, while historically cyclical recessions last 18 months - and tend to follow years of leveraged prosperity of Gatsby-like proportions. Considering that in this most recent leveraged cycle from 2002-07, we reached a point where a record 40% of corporate profits were derived from financial activities, where household debt relative to income and assets surged to unprecedented levels and the personal savings rate briefly went negative at the height of the housing bubble, it is safe to say the down-cycle we are currently experiencing did indeed follow a classic elongated period of leveraged prosperity. It is now reverting to the mean.
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some rather scary numbers:

• $6 trillion - The amount of private sector debt that needs to be eliminated (Based on ML data that total private sector credit market debt relative to national income is still near a record-high of 140 per cent vs a long-run norm of 80 per cent).
• $1 trillion - The amount of excess capacity in the US economy.
• $13 trillion - the cumulative loss of household net worth at the end of 2008.
• 70% - The US's share of global consumer spending/GDP, which Rosenberg predicts will now revert to its long-run average of 64 per cent.