How the NBER Determines When Recessions End

The National Bureau of Economic Research, the semi-official arbiter of recessions in the U.S., defines recessions as periods when a significant decline in economic activity, spread across the economy, lasts more than a few months, as measured by real gross domestic product, real income, employment, industrial production and retail sales.

Their analysis of when a recovery starts looks for turning points: when unemployment stops climbing, when growth stops plunging, when industrial production starts rising again.