In less than a decade, Sea-Tac International Airport has gone from the 17th busiest airport in the country to the 8th. 

Beginning Friday, it expects to handle about 170,000 daily passengers this summer, that's up to 15.6 million people. 

While that sounds like blistering growth, the rate of growth has actually slowed to a projected 4% this year and perhaps 3% next year. It was as high as 12.9% in 2015. 

“A small percentage of a big number is still a big number,” says Lance Lyttle, Sea-Tac’s Managing Director.

The airport is coping, but he says it is still behind the curve. The growth reflects demand based on the the overall economic acceleration in the Seattle-Tacoma metropolitan economy, far outstripping earlier forecasts.

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The port has some 100 projects in the works, or in planning, to cope with that growth. Those projects include expansion and upgrades to the north satellite, known as NorthStar, and a new International Arrivals Facility, which includes a giant sky bridge. The sky bridge is due to be complete later this year, which will connect the IAF to the south satellite, where planes will actually park. That sky bridge will be high enough to clear a 747.

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Behind the scenes, the baggage system is being completely rebuilt into one integrated system out of multiple legacy systems built up over previous decades. The first phase of the baggage system is due to be operational by late 2019 or early 2020. But it’s so big, the final pieces won’t be running until 2025.

In total, the Port of Seattle has slated $3.7 billion dollars for projects. Security remains a constraint, and the port plans to expand two checkpoints soon, including a new lane at check point 4 by this weekend. A new checkpoint is slated for construction in about a year.

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