Recessions since World War II have lasted just over 10 months each, on average.

The last one, which began in 2020, lasted just two months.

In the United States, though, the National Bureau of Economic Research, a century-old nonprofit widely considered the arbiter of recessions and expansions, takes a broader view.

According to the bureau, a recession is “a significant decline in economic activity” that is widespread and lasts several months.

Some can happen back-to-back, like the recession that began and ended in 1980, and the next, which started the following year, according to the bureau.

On average, recessions since World War II have lasted just over 10 months each, according to the N.B.E.R., but of course there are some that stand out.

The Great Depression, which is seared in the memories of older Americans, began in 1929 and ended four years later, though many economists and historians define it more broadly, saying it didn’t end until 1941, when the economy mobilized for the nation’s entry into World War II.

The last two recessions highlight just how different they can be: The Great Recession lasted for 18 months after starting in late 2007 with the bursting of the housing bubble and resulting financial crisis.

The recession at the height of the coronavirus pandemic in 2020 went on for just two months, making it the shortest ever, even though the downturn was a brutal experience for many people.

“In terms of just the sheer amount of contraction of real activity and this rapidity the Covid contraction was the most spectacular,” said Robert Hall, chair of the National Bureau of Economic Research’s Business Cycle Dating Committee, which keeps track of recessions.

One response might include targeted tax cuts or spending increases on safety net programs like unemployment insurance that kick in automatically to stabilize the economy when it is underperforming

A more active approach might involve Congress’s approving new spending on, say, infrastructure projects in order to stimulate the economy by adding jobs, increasing economic output and boosting productivity — though that could be a difficult proposition right now because that kind of spending could worsen the inflation problem