Oct. 19--American manufacturers have started to come back after suffering the deepest, most prolonged collapse since the Great Depression.

But manufacturing's recovery will likely be slow, and job losses will continue to mount for quite some time, economists and manufacturing executives say.

"There's shared pain throughout," said Ron Bullock, chairman and chief executive officer of Bison Gear & Engineering Corp.

Sales have dropped 20 percent during the past year at Mr. Bullock's 49-year-old firm, which produces power-transmission and motion-control products in St. Charles, Ill.

Bison's work force has declined from 300 before the recession began to 215 today. There's no overtime. And salaries have been frozen.

Despite the grueling recession, the industry has its optimists.

"The facts clearly illustrate that manufacturing is central to America's economic future," said Emily Stover DeRocco, president of the Manufacturing Institute.

"The United States has the largest manufacturing economy in the world, producing $1.6 trillion in goods annually," Ms. DeRocco said. She points out that productivity growth is higher in manufacturing than in other sectors. This long-term trend has helped to hold down inflation and has contributed to a higher standard of living.

"Manufacturing continues to generate more economic activity per dollar of production than any other business sector in the country," Ms. DeRocco said. "And manufacturing drives innovation by conducting nearly half of all research and development and creating the bulk of technology in the nation."

Manufacturing production, which represents about 12 percent of gross domestic product (GDP), reached its all-time peak in December 2007 -- when the recession began.

During the next 18 months, manufacturing output plunged 17 percent, according to Federal Reserve Board data. Factory production finally began rising in July and continued expanding in August and September, the Fed reported.

However, factory output may not return to its pre-recession level until 2014, said David Huether, chief economist for the National Association of Manufacturers (NAM), an industry trade group.

"Manufacturing output will continue to considerably lag the growth rate of the overall economy, creating tremendous problems for the U.S. economy," said Alan Tonelson, a research fellow at the U.S. Business and Industry Council, a national business organization whose 1,900 members are mainly small and medium-sized domestic manufacturers.

"If we want to increase our living standards, we can't just increase savings. We must increase production," said Mr. Tonelson.

Manufacturing employment has already lost more than 2 million jobs since the recession began, according to the Bureau of Labor Statistics.

Employment in manufacturing industries will likely continue to fall through the middle of next year, Mr. Huether said. Then, during the next 4 1/2 years, from mid-2010 through the end of 2014, only 43 percent of those lost jobs will return, according to the NAM forecast.

The depth of manufacturing's collapse was breathtaking, not only in the United States, but worldwide as well.

Between December 2007 and June 2009, U.S. factory output plunged 17 percent. That's nearly five times the 3.7 percent decline in the entire economy. The 17 percent plunge in factory output is also nearly twice the 8.8 percent decline suffered during the 1981-82 recession, when the overall unemployment rate reached a postwar high of 10.8 percent. The U.S. unemployment rate hit a 26-year high of 9.8 percent in September.

When the industry hit bottom in June 2009, manufacturing output had fallen below production levels of June 1998.

Since the beginning of the recession, manufacturing employment has plummeted by 15 percent, much more steeply than the proportion of manufacturing job losses experienced during the 1973-75 recession (10.2 percent) and the 1981-82 downturn (11 percent).