It is part of the $3.9 billion terminal built at LaGuardia to replace terminals C and D.
The new concourse opens to travelers on Monday.
"The opening of the first new concourse at Terminal C is a major milestone that takes us one step closer to transforming LaGuardia Airport into a global gateway worthy of this state," Governor Cuomo said Tuesday. "We're building the nation's first completely new airport in 25 years and showing the nation and the world that you can be ambitious and get big things done."
Delta operates more than 275 peak-day departures from its LaGuardia hub and is celebrating 50 years serving the airport.
The new terminal features 37 gates across four concourses. There is also a new, larger Delta Sky Club with a Sky Deck.
"Two years ago, we set out to build a state-of-the-art facility at LaGuardia Airport, an airport that our customers and the people of New York deserve. Thanks to the commitment and hard work of the Delta team and our many partners, today marks the beginning of a new era for millions of Delta customers at LaGuardia. The excitement that is building here is palpable and contagious, and we are already looking ahead to many more milestones to come," said Ed Bastian, Delta CEO.
The work also includes dual taxi lanes to reduce wait times and larger gate areas.
There is still a push for an air train that would link LaGuardia with Penn Station and Grand Central.
WATCH: Delta opens new concourse at LaGuardia
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