Delta Air Lines Inc. on Thursday said it would add first-class seating to domestic flights longer than 750 miles or about 2.5-hours long this fall.
Once upgrades are completed, 50 routes that feature Delta Connection flights with just one service class will have both first and economy class, the company said.
Meals and linen service are offered on all regional flights that feature a first-class cabin, Delta said. It also said airplanes that have first class include Embraer and Bombardier models.
The moves are part of Delta's plan to spend $1 billion in coming years on upgrades that include equipping some planes with flat-bed seats that offer extra legroom and adding amenities such as more overhead bin space.
Atlanta-based Delta, the world's biggest airline, is also looking to attract more business travelers and bolster its presence in high-growth cities such as New York.
For example, in May, the company said it would add more flights between New York and business centers such as London, Moscow and Milan.
Separately on Thursday, Delta said that Vietnam Airlines is joining its SkyTeam global airline alliance, which includes Air France-KLM and China Southern Airlines.