Boeing will add a fourth assembly line to produce more 737 Max aircraft, as it tries to more quickly translate a backlog of orders into cash-generating deliveries of new planes.

The new line will open in the second half of next year, according to a note Monday to employees from Stan Deal, the CEO of Boeing’s commercial-planes business.

The line will be in an existing facility in Everett, Washington, where space is available because Boeing is shifting production of larger 787s to South Carolina and ending production of the iconic 747.

The plant is about 40 miles north of Boeing’s other 737 assembly lines in the Seattle suburb of Renton, one of which has been idle but is being reactivated, Deal said. He said the the company is not relocating the entire 737 program, just adding capacity, especially for newer models of the Max.

The Max is Boeing’s best-selling plane. It was grounded worldwide for nearly two years after two deadly crashes involving a flight-control system that Boeing later overhauled. Since U.S. and other regulators cleared the Max to resume flying, Boeing has landed large orders from United, Delta, Southwest, and foreign airlines.