As part of an overhaul of its domestic fleet, Atlanta-based Delta Air Lines will purchase 100 "next-generation" 737-900ER (extended-range) jets from Boeing.
The order has a list-price value of more than $8.5 billion, according to Boeing.
Delta will take delivery of the extended-range 737s between 2013 and 2018 as the airline retires its older mainline jets.
"The order will enable Delta to add 100 fuel-efficient, state-of-the-art 180-seat aircraft to its fleet, replacing on a capacity-neutral basis older technology aircraft that will be retired from the fleet," the company said in a news release.
"The new aircraft will improve the company's profitability while providing customers with an industry-leading on-board experience."
With a range of 3,200 nautical miles, the extended-range Boeing jets will be able to handle any domestic route offered by Delta, the airline said.
"I want to commend all the manufacturers who participated in this process," said Richard Anderson, Delta's chief executive officer.
"Their innovation in developing fleet solutions for the future resulted in several very competitive proposals."
The aircraft will be equipped with CFM56-7B engines produced by CFM International, a joint venture of General Electric and Snecma of France.
Delta noted that it will begin taking deliveries of the aircraft in the second half of 2013.
The airline will receive 12 jets in 2013, 19 per year in 2014 through 2017, and the remaining 12 in 2018.
Each aircraft has committed long-term financing, Delta said.
Thanks to "maintenance efficiencies" and a 15% to 20% per-seat improvement in fuel consumption, the airline anticipates lower units costs compared with the Boeing 757 and 767 and Airbus A320 aircraft that the new Boeing jets will replace.
"With significant savings from increased fuel efficiency and lower maintenance costs, these aircraft will be cash-flow positive and earnings-accretive from the first year of operation," Anderson said.
The 737-900ER will be Delta's first aircraft to feature Boeing's new "Sky Interior," which offers expanded carry-on baggage space; a roomier cabin; and an LED lighting system that provides softer color schemes.
Delta is more than halfway through a $2 billion, three-year investment to boost revenues by improving the customer experience.
The investments include improvements to Delta's fleet, facilities and technology.
Recent upgrades have included the installation of full flat-bed seats in the business-class cabin of all Boeing 777 and 767-400ER aircraft, for international flights; additional legroom and recline on the first few rows of coach seating in certain Boeing and Airbus jets; and in-flight Wi-Fi on a growing number of domestic flights.