Sun Country Airlines is adding 19 seasonal routes this spring in its largest expansion ever, with eight from Minneapolis-St. Paul International Airport including one to Chicago with a $49 starting price.

It's the biggest leap yet by Eagan-based Sun Country as it transforms from a middle-tier, Twin Cities-centric airline to an ultra-low-cost carrier with national reach.

The airline also said it will add about 160 jobs in the Twin Cities, a 10 percent jump in employment, and confirmed a plan to move its corporate office to one of its hangars at the airport. It said it will buy five new planes in 2019, though the additional routes aren't contingent on the purchases.

"We are going to carry about 40 percent more passengers this year than last," Jude Bricker, Sun Country's chief executive, said at a news conference at the airport. The airline flew just under 2 million passengers for the 12 months that ended last Sept. 30, the latest period for which data is available from the federal Bureau of Transportation Statistics.

Sun Country is also growing in several other markets where executives believe leisure travelers don't have access to low fares. The airline over the last year and a half has been lowering its base airfares while increasing the number of optional services and fees. Its route expansion may lead rival airlines to lower or even match Sun Country's fares.

"This is going to stimulate air travel. It brings downward pressure on airfares," said Brian Ryks, chief executive of the Metropolitan Airports Commission, who also attended the news conference.

Twin Cities passengers will soon have nonstop access on Sun Country to Chicago O'Hare, Washington Dulles, Newark, Philadelphia, Providence, R.I., Sacramento, San Antonio and St. Louis.

Sun Country will fly four times a week to all eight destinations, which have staggered start dates between April and June. Seasonal service will end between Labor Day and late October, depending on the route.

The initial one-way starting fares range from $49 between MSP and O'Hare to $119 between MSP and Sacramento. An average round-trip fare between MSP and O'Hare was $249 over the last two weeks, according to Kayak, an online ticket aggregator.

Another ultra-low-cost carrier, Spirit Airlines, kept price pressure on the MSP-Chicago route until abandoning it last year. Chicago is consistently one of the most popular destinations from MSP and Sun Country executives saw a chance to attract passengers by reinstating low fares for summer travel there, Bricker said.

He took the helm of Sun Country in the summer of 2017 under the airline's previous ownership and created an aggressive growth strategy that hinged on the airline getting its costs under control. Its new owners, private-equity firm Apollo Global Management, infused $90 million into the airline last year.

On Tuesday, Sun Country also unveiled new routes from Nashville, Portland and Dallas-Fort Worth, which have become focal markets for it because travelers there face higher fares on certain leisure destinations, as well as at Las Vegas and San Francisco.

The expansion reinforces Sun Country's position as a seasonal airline adept at ramping up and drawing down services many times throughout the year and at many different airports.

"Seasonal markets will make up the vast majority of our network in perpetuity and that's because we carry leisure travelers," Bricker said. "So we have to be a carrier that can fly a lot when people want to travel and then no fly when people don't, and that's the business we are building."

Some of the MSP routes are a comeback for Sun Country. The airline flew to Chicago's Midway International Airport until late 2015. It last flew to Chicago O'Hare and San Antonio in 2001 and Dulles in 2010.

Sun Country currently operates seasonal service from Minneapolis-St. Paul to New York's John F. Kennedy International Airport. An airline spokesperson says executives haven't decided whether it will continue to fly there once the Newark service begins.

This will be the first time Sun Country has ever flown to the other new destinations on the MSP routes.

Of the 160 nonstop destinations reachable from MSP, 60 of them are now what airport officials deem "competitive," meaning more than one airline flies the route.

While Sun Country isn't targeting business travelers, Ryks said those business employees have families — here and around the country — who book these fares.

"Sun Country's added network capacity will help ... bring in more people to our world-class city," Minneapolis Mayor Jacob Frey said at the news conference.

While Tuesday's event was celebratory, Bricker also acknowledged problems for the airline last year as it made changes. Passengers have been frustrated by lapses in the airline's customer service communications, delayed and mishandled baggage and the switch to an ultra-low-fare model, which some view as punitive and others see as a bargain.

"Change was hard on our employees. It's hard for everyone," Bricker said. "We've had some operational challenges as we struggle through things like government shutdown and its effect on TSA at the airport. And, when you grow that rapidly, sometimes your infrastructure can be strained a little bit."

But he said the airline is now delivering service that's "a little bit better" than Spirit and Frontier airlines. "And we think we can match them on costs," he added.

Kristen Leigh Painter • 612-673-4767