Seattle ? Boeing Co. will open a second assembly line for its long-delayed 787 jetliner in South Carolina, expanding beyond its longtime manufacturing base in Washington state to take advantage of economic incentives and a nonunion work force.

The Chicago-based airplane maker said Wednesday it chose the site in North Charleston over Everett, Wash., because it best suited plans to boost production of the highly anticipated jet, designed to carry up to 250 passengers.

The decision ended an interstate competition for the huge factory, with South Carolina prevailing over the state where Boeing has built airplanes for decades. It hands South Carolina production of a plane crucial to Boeing’s future but one plagued by problems stemming partly from the company’s reliance on suppliers spanning the globe.

South Carolina offered Boeing $170 million in incentives and relief from sales taxes on things like fuel used in test flights.

The move wasn’t entirely unexpected. Boeing already operates a factory in North Charleston that makes 787 parts and owns a 50-percent stake in another plant that also produces sections of the plane, Boeing’s best-selling new aircraft to date.