The number of weekly hours U.S. factory workers put in last month climbed to nearly 42 hours, matching levels American workers saw during World War II, an analysis of Labor Department data shows.

The department's latest data show the 41.9 hours-per-week figure is one of the highest in recent history for nonfarm payrolls, tied only with manufacturing hours reached during robust economic periods in 1997 and 1998. The record is 45.4 hours, which was set in January and February of 1944.

If the demand stays steady, employers will be forced to consider hiring for future needs, not just for immediate openings, said John Challenger, chief executive officer of Challenger Gray & Christmas Inc., an employment consulting firm based in Chicago.

Even as manufacturing employers have shifted away from union jobs to lower-paying non-union ones, research from the Commerce Department found that hours worked plus wages and benefits gave factory workers up to a 17 percent advantage over workers with similar skills in other industries.

January figures from the Commerce Department show that the average hourly earnings for a manufacturing production worker was $19.23, compared with $19.97 for the private sector as a whole, but the high number of hours worked is what makes the difference. Mark Doms, undersecretary for economic affairs of the Commerce Department, says that factory employees tend to work more hours per week and more weeks per year than other workers, which helps explain the advantage.

"When you're trying to compare apples to apples," Doms said in a recent interview, "you do see this manufacturing wage premium has been robust over time."

Factories have added 500,000 jobs to the recovering economy since the end of 2009 and the industry consistently demonstrates high productivity, up 2.2 percent above the 2012 level, compared with the rest of the private sector, which rose only 0.7 percent, according to the latest figures from the Bureau of Labor Statistics.

"When you have to start to pay people time-and-a-half, and you have the volume of business, you can justify hiring people," Michael Montgomery, U.S. economist at IHS Global Insight in Lexington, Mass., told Bloomberg News.