The Boeing logo is seen at their headquarters in Chicago, in this April 24, 2013 file photo. REUTERS/Jim Young/File Photo

(Reuters) - Boeing Co BA.N said on Thursday it opened its first commercial airplane plant in St. Louis that is expected to add about 700 jobs by early 2020, when the company is scheduled to start deliveries of the 777X.

The world's biggest airplane maker said it had committed more than $300 million to build the 424,000-square-foot plant, which will initially make composite parts for the 777X, the company's newest jetliner. (bit.ly/2e0KoeP)

Production of 777X wing edge and tail parts is expected to begin at the plant in early 2017, the company said.

Boeing opened a $1 billion factory in Washington state in May that will make carbon-composite wings for the 777X. (reut.rs/2e0XpVF)

The future of some of Boeing’s facilities in St. Louis, where the company currently has about 15,000 employees, had been in question due to slowing fighter jet sales.

Boeing had 306 orders for the 777X through September. The 777X replaces the highly successful 777, introduced in 1995.

Boeing plans two versions of the 777X, the -8 with about 350 seats and a range of 9,300 nautical miles, and the -9 with about 400 seats and a range of 8,200 nautical miles.