From yesterday: We're very likely in a recession now, but since it hasn't yet been officially announced by the NBER, let me wish the current U.S. economic expansion a "Happy Seventh Birthday"!
According to the Business Cycle Dating Committee of the National Bureau of Economic Research, "a trough in business activity occurred in the U.S. economy in November 2001. The trough marks the end of the recession that began in March 2001 and the beginning of an expansion." So the current economic expansion actually started in November 2001, and therefore the 7th year of the expansion started a month ago, and until the official decision is announced we're in the 86th month of an economic expansion.
Update: The last economic expansion lasted only 73 months.
The NBER's historical business cycle data show that the average economic expansion since WWII lasted 57 months (4 years, 9 months). In that case, the current expansion is more than two years longer than the average expansion, depending on when the NBER decides the next recession starts.
UPDATE: Cancel the economic expansion's birthday party, and get ready to "celebrate" the first anniversary of the economic recession of 2008-2009. The NBER just announced that the economic expansion ended in December 2007, and we've been in recession since January 2008.