Finally, officially, the 1990-91 recession is over.

In fact, it ended way back in March 1991, according to an announcement yesterday by the group that makes such calls.

That means the economic recovery, though weak, began 20 months before last month's election, when economic woes helped cost President Bush a second term.

The recession began in August 1990, as Iraqi forces invaded and overran Kuwait, and lasted eight months, the National Bureau of Economic Research said.

The business cycle dating committee of the bureau, a private economic research organization that has been pegging the beginnings and ends of recessions since the 1920s, waited so long to declare the recession over because of the slow, halting recovery that followed it.

"The committee had waited to make the determination of the trough {bottom} date until it was confident that any future downturn in the economy would be considered a new recession and not a continuation of the recession that began in July 1990," the bureau's announcement said.

It took so long because the committee simply was not sure until this month that the economy might not turn down again before it got back to the level of activity it had reached before the recession began.

That professional caution had a major impact on the language used to describe the state of the economy, and perhaps even on the fates of the presidential contenders.

As recently as last week, President-elect Clinton still was referring at his economic summit conference to "this prolonged recession," even though most analysts had thought for a year and a half that the bureau should pick March or April 1991 as the recession's end.

In one of the presidential primary debates in March, Clinton labeled the slump "a three-year recession, which is the worst since before World War II."

On the "Larry King Live" show in October, President Bush observed -- inaccurately -- that "the national definition of a recession, I believe, is two consecutive quarters of negative growth.

"Now, your listeners may have trouble believing this," Bush continued, accurately. "We have had five quarters of positive growth in a row. So when I said there isn't a recession last fall, technically I was right.

"But I should have done it recognizing that there's a hell of a lot of people hurting. And I feel it. And I knew it then and I know it now. But I think some of that's what the opposition homed in on. They said the president is out of touch. He says we're not in a recession."

Only with the data that became available this month -- on industrial production, employment, business sales, gross domestic product (GDP) and other indicators that it uses for calculating business cycles -- could the bureau committee be confident that any new downturn should be considered a separate recession.

The notion that two consecutive quarters of decline in inflation-adjusted GDP defines a recession is a widespread misperception. Actually the bureau looks at a wide array of data -- including monthly figures for employment, unemployment, personal income, industrial production, business sales and other indicators, as well as quarterly estimates of GDP -- to pick the month in which an economic expansion peaked and the month in which the recession hit bottom.

A pickup in growth in the third quarter of this year helped the committee make up its mind, because the July-September rise in GDP finally pushed that broad measure of the economy's total output of goods and services above the peak it reached in the second quarter of 1990 prior to the recession.

The Commerce Department yesterday revised downward to 3.4 percent its previous estimate that third-quarter growth was at a 3.9 percent rate. Additional data showed a smaller increase than reported previously in business inventories, and a larger trade deficit, both of which tend to reduce U.S. production. The department's first estimate of the third-quarter number had been 2.7 percent.

Separately, the department said its quarterly survey of business intentions to invest in new plants and equipment showed companies planning to increase such spending next year by 7.6 percent, after adjustment for inflation, compared with an expected 5.4 percent rise this year. Almost all manufacturing industries are planning higher investment spending except the aircraft industry, the department said.