United Airlines began its service out of Paine Field in Everett on Sunday.
The airline joins Alaska Airlines in offering daily flights out of the new terminal to both Denver and San Francisco.
United said it is excited to return to the airfield where the company first flew out of more than 80 years ago.
The addition of United also brings the terminal to full operation.
Alaska Airlines began flying out of Paine Field on March 4. The original opening date was delayed after the airline pushed out its first day of service during the federal government shutdown at the beginning of the year.
More news from KIRO 7
© 2020 Cox Media Group