Even so, the impact on the American job market has been modest so far. Much of the work brought back has been high-value-added, automated production that requires few actual workers, which is part of the reason America’s higher wages are not scaring off companies.

American manufacturing has been growing in the last two years, but the sector still has two million fewer jobs than it had when the recession began in December 2007. Worldwide manufacturing appears to be growing much faster, even for many of the American-owned companies that are expanding at home. General Electric, for example, has hired American workers to build water heaters, refrigerators, dishwashers and high-efficiency topload washers, but continues to add more jobs overseas as well.

Apple has not announced plans to move the complex, faster-growing portions of its product lines. Macs now represent a relatively small part of Apple’s business, accounting for less than 20 percent of its nearly $36 billion in revenue in its most recent quarter. The company’s iPad and iPhone products, which amount to nearly 70 percent of its sales, will continue to be made in low-cost centers of manufacturing like China, mostly on contract with outside companies like Foxconn.

Mr. Cook’s statements suggested Apple was planning to build more of the Mac’s components domestically, but with partners. He told Bloomberg Businessweek that the plan “doesn’t mean that Apple will do it ourselves, but we’ll be working with people, and we’ll be investing our money.”

Whether Apple’s newly announced plan might help create other higher-paying jobs along the supply line depends on the nature of the manufacturing.

Other computer manufacturing has been trickling back to the United States after largely shifting overseas in the 1990s.