NEW YORK (AP) — Southwest Airlines is placing an order for 208 Boeing 737s with a value of nearly $19 billion.

The Dallas airline, which operates an all-Boeing fleet, said Tuesday it 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 whole $19 billion.

Southwest Airlines Co. has bought more 737s than any other airline. Boeing says Southwest 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.