GREENSBORO, N.C. — Heavy-duty truck maker Mack Trucks Inc. will move its Allentown headquarters to North Carolina as part of a restructuring that could cost Pennsylvania as many as 600 jobs.

The headquarters' move to Greensboro is scheduled for next year.

Mack also plans, later this year, to shift assembly of highway vehicles from Virginia's New River Valley plant to the Mack plant in Macungie, Pa. The move is expected to add about 200 blue-collar jobs in Pennsylvania, helping offset some of the loss of office jobs.

Mack currently employs about 1,500 in Pennsylvania's Lehigh Valley, including 680 at its headquarters. Total employment in the state should total at least 900 after the restructuring, said John Mies, Mack vice president of communications.

The company is also converting a test center in Allentown into a customer demonstration and reception center.

In addition, Mack will close warehouses in Columbus, Ohio, and Dallas and will downsize facilities in Baltimore, Chicago, Jacksonville and Memphis.

The headquarters move allows Mack Trucks to join fellow Volvo Group subsidiary Volvo Trucks North America in Greensboro. Sweden-based Volvo Group is the second-largest producer of heavy trucks. Many of Mack's support functions, including information technology, human resources and finance, are already stationed in Greensboro.