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By Daniel Lovering, The Associated Press

CHARLESTON, S.C. – said Wednesday it will open a second assembly line for its long-delayed 787 jetliner in South Carolina, expanding beyond its longtime manufacturing base in Washington state.

The Chicago-based airplane maker said it chose North Charleston over Everett, Wash., because the location worked best as the company boosts production of the mid-size jet, designed to carry up to 250 passengers.

Boeing already operates a factory in North Charleston that makes 787 parts and owns a 50-percent stake in another plant there that also makes sections of the plane.

For years, Boeing has discussed the possibility of expanding production of the 787 to meet demand for the plane, its best-selling new aircraft to date. About 55 airlines have ordered some 840 of the planes since the program was launched in 2003 – far more than any other Boeing plane at the same stage of development.

"Establishing a second 787 assembly line in Charleston will expand our production capability to meet the market demand," Jim Albaugh, president and CEO of Boeing’s commercial airplane division, said in a statement.

Boeing hasn’t indicated how long it will take to get the second assembly line up and running, but the company says it hopes to produce 10 of the planes per month by 2013. It currently makes about 31 of its smaller 737s per month and seven of its popular 777s per month.

The decision allows Boeing to build on relationships the company has established in South Carolina, strengthen its competitiveness and sustainability, and help it grow in the long term, he said.

Everett is the site of Boeing’s commercial aircraft division, where the company has assembled early versions of the 787.

The first flight and deliveries of the high-tech aircraft have been postponed repeatedly due to manufacturing glitches and a labor strike. A walkout by union machinists late last year forced the company to shut its commercial plane operations for eight weeks. Labor relations were considered key to Washington state’s bid to keep 787 production in the state.

Besides South Carolina, states initially seen as competitors to Washington included North Carolina, Kansas, Texas and California. But Boeing said last week it had narrowed the choices to Washington and South Carolina.

The news came shortly after South Carolina legislators approved an economic incentive package believed to be tailored to lure the Boeing assembly plant to the state. The incentive package would allow lawmakers to guarantee tax breaks and low-interest loans for an unidentified economic development prospect.

After Boeing announced its decision, the typically staid South Carolina Senate chamber broke out in cheers and legislators put on palmetto tree pins with wings, merging the state’s symbol with its biggest economic development announcement on record.

Gov. Mark Sanford called it a "monumental" investment that will spur the state’s already-growing aerospace hub.

Boeing claims the 787, made of lighter-weight materials, will be more efficient, quieter and have lower emissions than other airplanes. The plane will include wider seats and aisles, larger windows and a ventilation system meant to allow for higher humidity. Those features, Boeing says, will make the cabin more comfortable.

Unlike Boeing’s other commercial jets, the 787 will be built mostly from lightweight carbon composite parts instead of aluminum. Boeing has relied on overseas suppliers to build huge sections of the plane that are later assembled in Everett.

That approach so far has proved problematic. Ill-fitting parts and other glitches have hampered production, and Boeing has postponed the plane’s inaugural test flight and deliveries five times, putting it more than two years behind schedule. Boeing reiterated last week that it plans to fly the 787 for the first time by the end of the year.

The delays have cost Boeing credibility and billions of dollars in anticipated costs and penalties.

Shares of Boeing rose $1.02, or about 2 percent, to $48.24 in after-hours trading. During the regular session, they slid 53 cents, or about 1 percent, to $47.22.