In an effort to get Minnesotans to leave home in the summer, Sun Country Airlines is offering four new destinations to northern U.S. cities, including the only nonstop flight from Minneapolis-St. Paul to Portland, Maine.

The other three seasonal routes from MSP will be to Cleveland, Baltimore/Washington and Bozeman, Mont. All four are new markets for the airline.

The routes reflect Sun Country's new strategy for growing its MSP hub during the summer months by offering routes to the east and west, rather than south.

The warm-weather months can be slow for Sun Country, which still depends heavily on its MSP customer base. Many Minnesotans prefer to visit the lake cabin rather than book flights to tropical destinations traditionally associated with the airline's route map.

Instead of accepting less-than-full flights, Sun Country reallocates its airplanes to other markets and sees opportunity to connect MSP passengers to some bigger U.S. cities during those summer months.

"Continuing to grow in our home market is key for us, and we want to continue to offer more service to the places Minnesotans want to go," Jude Bricker, the airline's chief executive, said Tuesday in a statement. "We are adding four unique destinations for our leisure travelers to escape to this summer, whether that be to visit family and friends or to explore these great cities."

In addition to these new MSP summer routes, Sun Country announced five new routes from Dane County Regional Airport in Madison, Wis., as well as three new summer destinations from Dallas-Fort Worth.

This reflects Sun Country's surgical strategy for its non-MSP markets. Bricker believes the small Minnesota airline has a chance to capture some traffic in "seasonally peaky" markets that have more than one key airline player. Unlike MSP where Delta Air Lines dominates and customers are more loyal to a particular airline, the Dallas-Fort Worth area has two big incumbents, Southwest and American airlines. Bricker said last month that he sees plenty of opportunity there as a low-cost carrier.

Sun Country started its aggressive growth campaign outside MSP in the summer of 2018. From 2017 to 2019, the airline's available seat miles — an industry measure for the amount of airline service — grew sixfold on non-MSP routes. Its capacity at MSP grew 13% in that time, and is still home to about 80% of its flight departures.

The expansion at times caused service disruptions. The more routes it offers, the lower the frequencies of those flights, which can be a problem for customers if a once-weekly or twice-weekly departure is seriously delayed or canceled. The airline was simultaneously implementing a series of changes aimed at modernizing their systems and cutting costs — from new technology to outsourcing baggage handling to updating its airplane cabins. If anything went awry with these transitions, customer-service backlogs and long lines would inevitably follow. These growing pains were made worse by an antiquated website that didn't allow customers to manage their own travel, forcing everyone through the phone and ticket-counter lines.

Airline executives said the worst of those hardships are behind them and are hoping the new self-service tools, like airport kiosks at MSP, and more agents in its call center will improve speed and convenience for its customers.

The new routes don't yet have an end date, but run at least through Aug. 24, 2020, which is as far out as is available currently on Sun Country's booking system.

None of the new MSP routes will operate daily and their frequencies and schedules will vary as follows:

• MSP to Baltimore/Washington: operates twice weekly beginning May 8 and increases to four times weekly on June 4, Sundays, Mondays, Thursdays and Fridays.

• MSP to Bozeman: service begins June 3, operates twice weekly on Wednesdays and Saturdays.

• MSP to Cleveland: service begins May 29, operates twice weekly on Sundays and Fridays.

• MSP to Portland, Maine: service begins June 18, operates twice weekly on Sundays and Thursdays.

The last time MSP had nonstop service to Portland, Maine, was in 2009 with Northwest Airlines before it merged with Delta.

From MSP today, Delta, Southwest and Spirit airlines fly nonstop to Baltimore, and Delta flies nonstop to Cleveland and Bozeman.