Low-cost carrier Frontier Airlines announced the expansion of its network by adding 21 new cities and 85 routes, increasing its destinations by 30 percent and doubling the number of total routes.

By spring 2018, the carrier will offer fares to 90 percent of the United States population — allowing travelers to save more than $1 billion through lower airfares. From Denver (DEN) alone, the airline announced 21 new routes. Other cities with major expansions include Miami (MIA), Orlando (MCO), Tampa (TPA), Buffalo (BUF) and Long Island (ISP).

“We are proud to announce the nationwide expansion of our unique brand of Low Fares Done Right which will empower millions more people to afford to fly,” said Barry Biffle, chief executive officer, Frontier Airlines.” We project this will save our customers over a billion dollars annually on their flights. These new flights will allow us to serve even more of America and make flying a truly affordable option.”

Frontier’s network expansion will include 85 new routes, almost double the number of non-stop routes. The new addition with provide passengers with more than 1,000 routes and expanded winter service in key southern markets.

The expansion comes as the carrier continues to take delivery of Airbus A321 and A320neo aircraft.