Alaska Airlines' (ALK) acquisition of Hawaiian Airlines (HA) received the approval of the Department of Transportation (DOT) Tuesday after the airlines agreed to a number of terms designed to protect travelers.

The conditions include guaranteeing the value of the airlines' respective mileage rewards programs will be retained through the deal, and keeping a number of routes connecting Hawaii's islands to each other, Honolulu to the continental U.S., and serving rural areas of Alaska. The airlines also agreed to adopt policies like fee-free family seating and discounts for military families given their presence in Hawaii and Alaska, the DOT said Tuesday.

“Our top priority is protecting the traveling public’s interest in this merger," DOT Secretary Pete Buttigieg said. "We have secured binding protections that maintain critical flight services for communities, ensure smaller airlines can access the Honolulu hub airport, lower costs for families and service members, and preserve the value of rewards miles against devaluation."

Merger Moves Forward Following DOJ, DOT Reviews

The airlines announced the $1.9 billion deal in Dec. 2023, and last month reached the end of an antitrust review period without any competitive issues being raised by the Department of Justice (DOJ).

The companies said in a release following the DOT's approval that they plan to close the deal "in the coming days," and announced a merger team to lead Hawaiian Airlines until they receive a single operating certificate from the Federal Aviation Administration (FAA), allowing them to operate multiple airlines under one parent company, Alaska Air Group.

Shares of Alaska and Hawaiian Airlines were little changed in pre-market trading Wednesday following the news.