Spirit Airlines is making big moves at Detroit Metropolitan Wayne County Airport (DTW), an airport historically dominated by Delta Air Lines.

The Dania Beach-based carrier announced on Wednesday that its yellow Airbus jets will soon be flying 15 new and resumption routes from Detroit. Nine of the routes represent all-new service, while six of them represent resumptions.

In terms of additions, Spirit will add the following destinations from DTW beginning during the peak summer season.

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• Birmingham, Alabama
• Hartford, Connecticut
• Louisville, Kentucky
• Milwaukee
• Norfolk, Virginia
• Punta Cana in the Dominican Republic
• Richmond, Virginia
• Salt Lake City
• St. Louis

You’ll find the full details of the frequencies and start dates at the bottom of the story, but highlights include going up against Delta on a key hub-to-hub route from Detroit to Salt Lake City.

In fact, every single new Spirit destination from Detroit is already served by Delta, meaning that Spirit will likely need to compete on fares to attract flyers from the city’s biggest airline. (That could, in theory, lead to lower fares on Delta, which will no longer enjoy a monopoly in these markets.)

Detroit is an operating base for Spirit, and adding more flights there follows the carrier’s recent network strategy of growing in some of the biggest cities across the country. In the past, Spirit has largely targeted point-to-point routes in places that the major network carriers might’ve overflown.

But as the airline emerges from bankruptcy and looks to boost profitability, it’s continuing to compete head-to-head against larger incumbents. With this addition, Spirit’s presence at DTW will grow to 40 destinations, which is the most nonstop routes Spirit has ever offered from the airport.

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“We’re adding even more popular travel options to our Detroit route map, giving our DTW Guests a variety of new destinations to discover across the country and beyond. Savvy Motor City travelers will soon enjoy even more options to enjoy Spirit’s elevated experience at a value unmatched by other carriers,” said John Kirby, Spirit’s network planning chief, in a statement shared with TPG.

The flights announced on Wednesday join other recently announced service from Detroit to a handful of destinations. They include Baltimore; Charlotte; Memphis; Pensacola, Florida; Raleigh; and San Antonio — all starting in May.

When all is said and done, the airline will operate up to 48 peak-day departures in June. That makes Spirit the second-largest airline at DTW after Delta, which plans to operate more than 350 peak-day flights from Detroit in June.

While much of the expansion is focused on Detroit, Spirit is also adding three new routes in other markets. This includes:

• Hartford — Nashville, twice weekly beginning on Aug. 15
• Raleigh-Durham — Nashville, four times weekly beginning Sept. 4
• New York — Indianapolis, four times weekly starting Sept. 5

All of the new flights are already available for sale.