Regional carrier SkyWest has ordered 60 Embraer E175 aircraft and has options on 50 more.
The airline operates flights for Delta Connection, American Eagle, United Express and Alaska Airlines.
Sixteen of the ordered planes will be operated under contract with Delta, with deliveries beginning in 2027. They will be used as replacements for older Bombardier CRJ 700 and 900 planes.
The remaining 44 aircraft, slated for delivery between 2028 and 2032, will ready SkyWest for additional opportunities in contract flying.
U.S. carriers, including Delta, typically configure E175s with 70 or 76 seats, split between first class and coach cabins.
SkyWest is world's largest E175 operator with 263 aircraft. The list price for the 60-plane order is $3.6 billion, though airlines typically negotiate significantly discounted deals for bulk purchases.