Is Portugal in danger of becoming the next Iceland? (Read: small country on the edge of Europe overrun by masses of selfie-taking tourists.) Not yet, but you might want to book your trip sometime soon. Last year, a record 20 million visitors landed in Portugal, up nearly ten percent from the year before, and if anything, this year and next will see an even bigger influx. Fueling the boom: a sharp rise in the number of flights, especially across the Atlantic—and it’s only just beginning.

Already, there are more nonstop flights from the U.S. to Portugal than ever before, and in the height of summer, there were some 91 weekly flights to Lisbon as well as to Porto—almost twice as many as in 2017. Contrary to current trends, this isn’t due to an invasion by a brash budget carrier like Wow or Norwegian. Rather, the expansion has been fueled by TAP Air Portugal, a legacy flag airline that’s been flying over the North Atlantic for half a century. In the next year and a half, TAP is poised to double the number of cities it serves in North America—it currently flies to Boston, Miami, New York, Newark, and Toronto; up next are Chicago and Washington, D.C., which will see flight service begin in June 2019. San Francisco, though not officially confirmed, will likely get its first nonstops to Lisbon sometime in the next six months.

TAP has a whopping 71 Airbus planes on order, ranging from the fuel-efficient Airbus A330neo to the long-range narrowbody A321; by 2020, all of TAP's long-haul fleet will either be brand new or have been given an interior makeover. It certainly helps with the airline's plan to “focus on adding service to the States,” said David Neeleman, the JetBlue founder who became a co-owner of TAP by taking a substantial stake in the company three years ago. (Neeleman, who's fluent in Portuguese, was already running Azul, his Brazilian startup.)

Neeleman credits the airline’s stopover program, which allows layovers of up to three days in Lisbon or Porto for fliers en route to points beyond, for helping to create a buzz, predicting it will reel in an additional 150,000 customers annually. While three U.S. airlines also fly to Portugal, Neeleman notes that TAP is the only airline that can offer a stopover in its home country—and he said that once fliers get a taste of the country’s offerings, they’re more likely to return for a longer stay.

“I’d never been to Portugal until a few years ago, and no one else I knew had ever been there either,” he says.

“Now everyone I know has been to Portugal,” he cracked.

"I’d never been to Portugal until a few years ago, and no one else I knew had ever been there, either. Now everyone I know has been to Portugal."

So what else is he planning? Neeleman rattled off the wish list for new cities on its route map: a second West Coast gateway in Los Angeles; a Midwest foothold in Chicago and Houston, both major hubs for United, which is TAP’s biggest U.S. codeshare partner. When it takes delivery of the A321neo, the opportunities go up exponentially—using the narrowbody to hop the pond will facilitate nonstops between smaller markets. Starting next year, TAP plans to start flying to spots like Providence, Rhode Island and Hartford, Connecticut. If that formula sounds familiar, it’s because Norwegian last year began flying to some of those same secondary airports also with a narrowbody—the 737 Max—proving that passengers will tolerate a longer flight of up to seven hours on a single aisle plane, for the right price. Neeleman hasn’t said what fares will be, but TAP has its own version of a basic economy fare. There will be more nonstops to Porto, the northern gateway to wine country: This fall, TAP increased its Newark-Porto service to daily, and added Boston-Porto nonstops, as well.

TAP does offer more frills than the ultra-budget airlines that charge for meals and assigned seats. It just introduced a real business class, meaning it comes with fully lie-flat seats, wide seat-back screens and other amenities on the new A330neos, which started arriving in September; the widebodies will have 298 seats, including 34 business class and 96 coach seats with more legroom—31 inches of pitch, specifically.

Naturally, other airlines have taken notice of the Portugal boom: New this summer, Delta began flying nonstop from Atlanta to Lisbon and, until September 4, was flying five times a week from New York to the Azores (which few travelers could even find on a map a few years ago). United, for its part, flew a seasonal daily nonstop from Newark to Porto through October 3. Since 2016, the country has also added 100 new hotels.

How far can this go before Portugal becomes, well, the next overtourism poster child? There’s at least one brake on the boom, Neeleman points out—the limited capacity at Lisbon’s close-in airport, which has discouraged newbies like Wow from coming in. Government plans for a new airport to serve the capital have yet to move off the drawing board.

“Lisbon is very tough to get into,” Neeleman said. And that automatically gives TAP the homefield advantage.

This article was originally published in June. It has been updated with new information.