Mack Trucks Inc. said Friday it will cut 700 jobs, about 12% of its work force, by the end of July, with half of the layoffs coming in the Lehigh Valley, Pa. area.

The company said the reduction is related to a 37% decline in the truck market. It is Mack’s largest workforce reduction since the company closed its Allentown. Pa. assembly plant in 1987.

"It's clear that we will face a major drop in sales this year," Mack president and CEO Michel Gigou said. "This difficult decision is one part of an overall plan designed to maintain Mack's competitive position in an extremely challenging environment."

The construction truck assembly plant in Macungie, Pa. will lose 32% of its employees, cutting 300 jobs. The highway truck plant in Winnsboro, S.C. will lose 15% of its work force, or 135 positions. The engine and transmission plant in Hagerstown, Md. will have a 14% reduction in employment, or 150 jobs. An additional 130 positions company-wide will be removed by April 30, some by attrition.

Production will also be cut, and the Winnsboro plant will be idled the weeks of April 23 and 30 and June 4 and 25.