The unemployment rate jumped to 7.2 percent in December from 6.8 percent in November and 5 percent last April, when the recession was four months old and just beginning to bite. More than 11 million Americans are now unemployed, and their growing ranks seem likely to put pressure on President-elect Barack Obama and Congress to act quickly on a stimulus package that mixes tax cuts and public spending.

“These numbers, back to back, of more than a half million a month suggest that the U.S. economy is in a freefall,” said Nariman Behravesh, chief economist at IHS Global Insight. “It’s scary, and it indicates that unless something is done and done quickly to turn this economy around, we’re looking at an awful situation this year.”

The 7.2 percent was the highest unemployment rate since January 1993, when the country was still shaking off a jobless recovery from the 1990-91 recession. The loss in total jobs for 2008 was the largest since 1945.

The toll of job losses cut across every sector. Nearly 800,000 manufacturing jobs were lost in 2008, and 630,000 construction jobs disappeared as home-building slowed. Jobs dried up in the financial sector, in publishing houses and trucking companies, department stores and hotels.

“This is unprecedented,” said Mark Zandi, chief economist of Moody’s Economy.com. “It’s coast to coast. It’s everywhere. There’s really no refuge in this job market. There’s no safe place.”

“Even with a stimulus package, the unemployment rate is going to keep rising and by December it is likely to be over 9 percent,” said David A. Levy, chairman of the Jerome Levy Forecasting Center. In a speech on the economy, Mr. Obama said Thursday that the unemployment rate “could reach double digits.”

The accelerating job loss — more than one million jobs have disappeared in just two months — suggests that the recession will last at least into early summer, making it the longest since the 1930s. The severe recessions of the mid-1970s and early 1980s each lasted 16 months, the current record.

In his speech Thursday at George Mason University, Mr. Obama said that his American Recovery and Reinvestment Plan would “immediately jump-start job creation and long-term growth.” Most forecasters, however, say that even with an ambitious stimulus plan, the economy will continue to contract through the first half of the year, though at a slower pace — and even if a recovery does kick in by early summer, it won’t generate jobs for many months after.

“I would suspect that starting this past October and lasting through April, we will have really big job losses,” said Robert Barbera, chief economist at the Investment Technology Group, a research and trading firm.