Washington ? The nation’s employers, including some of its largest and most sturdy, announced plans Monday to slash more than 55,000 jobs, a staggering one-day toll that highlighted how quickly layoffs are accelerating and how widely misery is spreading throughout the labor market.

The cuts extended to companies that were once considered bright spots in the U.S. economy. Construction equipment maker Caterpillar, whose business last year was bolstered by strong exports, said it would cut 20,000 jobs. Pfizer, one of the giants of a health-care sector that had until recently seemed immune from the downturn, said it would cut 8,000.

In all, 22 of the 30 companies that are part of the Dow Jones industrial average have announced job cuts since the economy took a nosedive in October. Analysts say they’ve been surprised by just how quickly those cuts have added up. The number of people receiving unemployment insurance benefits now stands at 4.6 million, the highest level since 1982.

“These are not just numbers on a page,” President Obama told reporters at the White House Monday, as he urged Congress to pass his economic stimulus package. “These are working men and women whose lives have been disrupted. We owe it to each of them, and to every single American, to act with a sense of urgency and common purpose.”

The unemployment rate, at 7.2 percent nationwide as of December, has already reached 10 percent in some states, including Michigan and Rhode Island, the hardest hit. The nation has experienced the steepest rise in unemployment since the recession of the early 1980s, a recent analysis by the Economic Policy Institute found.

The job cuts announced Monday “are the predictable consequence of a quickly unraveling economy affecting all sectors and segments of the work force,” said Lawrence Mishel, the president of EPI. “Unfortunately, the rise in unemployment we’ve already had may only be halfway to where we’re heading.”

Construction firms, banks and automakers have been eliminating jobs for more than a year. But now positions are being cut across the economy. Those cuts signal that even financially strong companies are bracing for what they think will be a prolonged economic downturn.

Companies announcing job cuts Monday included Sprint Nextel, the wireless provider, which cut 8,000; Home Depot, which cut 7,000; General Motors, which laid off 2,000; and Texas Instruments, which cut 3,400.

Caterpillar, viewed as a stalwart of American industry, cut more jobs than any other company Monday. It said the economy has slowed so much in China and other once fast-growing nations that there have been fewer buyers for the company’s bulldozers, graders and other heavy equipment.

At Pfizer, the announcement of job cuts came after the firm said it would acquire Wyeth. While job cuts are typical after mergers, the recession played a role as well, analysts said. Drugmakers are facing increased regulation and competition from cheaper generics. Prescription drug spending in 2007 fell to its lowest growth rate in more than 30 years.