NEW YORK (AP) — Southwest Airlines Co. on Tuesday said it ordered 208 new Boeing 737 aircraft with a value of nearly $19 billion.

The Dallas airline, which operates an all-Boeing fleet, placed a firm order for 150 of the 737 Max, a new version of Boeing's most popular plane with more fuel-efficient engines. Southwest also ordered 58 next-generation 737s.

Because discounts are common, Southwest won't pay the full $19 billion list price.

Southwest has bought more 737s than any other airline. Boeing says Southwest, which flies more U.S. passengers than any other carrier, is the first customer to finalize an order for the 737 Max. Including this order, Boeing now has orders or commitments from 13 customers for more than 900 of the new model.

Southwest will receive the first 737 Max in 2017. Southwest CEO Gary Kelly has said publicly before that he considered buying planes from Boeing Co. rival Airbus if Boeing couldn't deliver a redesigned 737 before the end of the decade.

Before buying AirTran, Southwest only flew 737s. It has since inherited AirTran's fleet of 717s.

Last month, Boeing said Indonesia's Lion Air committed to pay $21.7 billion for 230 Boeing 737s. Lion Air also has options for 150 more planes, valued at $14 billion, bringing the deal's total potential value to $35 billion. But the Lion Air deal is not a certainty; it still has to finalize the order. Also in November, Emirates Airlines ordered $18 billion worth of 777s.

Both deals came shortly after Boeing finally began delivering its two newest planes, the next-generation 787 and the latest version of the iconic 747.

Boeing produces about one 737 every day in Renton, Wash. It is raising that to 42 per month in 2014.

Boeing shares rose 66 cents to $71.56 in premarket trading.