WASHINGTON (AP) - The longest recession the country has enduredsince World War II ended in June 2009, according to a group thatdates the beginning and end of recessions.

The National Bureau of Economic Research, a panel of academiceconomists based in Cambridge, Mass., says the recession lasted 18months. It started in December 2007 and ended in June 2009.Previously the longest postwar downturns were those in 1973-1975and in 1981-1982. Both of those lasted 16 months.

NBER's end date for the recession was consistent with thethinking of many private economists. The economy started growingagain in the July-to-September quarter of 2009, after a record fourstraight quarters of declines. Thus, the April-to-June quarter of2009, marked the last quarter when the economy was shrinking. Atthat time, it contracted just 0.7 percent, after suffering throughmuch deeper declines. That factored into the NBER's decision topinpoint the end of the recession in June.

Any future downturn in the economy would now mark the start of anew recession, not the continuation of the December 2007 recession,NBER said. That's important because if the economy starts shrinkingagain, it could mark the onset of a "double-dip" recession. Formany economists, the last time that happened was in 1981-82.

The NBER normally takes its time in declaring a recession hasstarted or ended.

For instance, the NBER announced in December 2008 that therecession had actually started one year earlier, in December 2007.

Similarly, it declared in July 2003 that the 2001 recession wasover. It actually ended 20 months earlier, in November 2001.

Its determination is of interest to economic historians - andpolitical leaders. Recessions that occur on their watch posepolitical risks.

In President George W. Bush's eight years in office, the UnitedStates fell into two recessions. The first started in March 2001and ended that November. The second one started in December 2007.

NBER's decision means little to ordinary Americans now muddlingthrough a sluggish economic recovery and a weak jobs market.Unemployment is 9.6 percent and has been stuck at high levels sincethe recession ended.