FACTBOX - U.S. recessions back to 1923

(Reuters) - The National Bureau of Economic Research's Business Cycle Dating Committee, the accepted arbiter of U.S. recessions, said on Monday that the U.S. economy tipped into a recession a year ago.

At 12 months and counting, the current recession is already the third longest since the Great Depression of the 1930s.

The NBER does not define a recession as two consecutive quarters of decline in real gross domestic product, as is the rule of thumb in many countries.

Rather, a recession is a significant decline in economic activity spread across the economy, lasting more than a few months, normally visible in real GDP, real income, employment, industrial production and wholesale-retail sales.

As a result, the NBER waits until there is conclusive evidence of a broad, lasting downturn before declaring the start of a recession. Since 1945, there have been 10 business cycles. The average recession has lasted 10 months, while the average expansion has spanned 57 months.

Below are the dates of recessions stretching back to 1923.

2001 RECESSION (eight months)

Began March 2001

Ended November 2001