Sea-Tac airport’s booming passenger volume makes it 9th busiest in U.S.

Record passenger travel through Seattle-Tacoma International Airport in 2016 vaulted the airport ahead of Houston, Phoenix, Miami and Charlotte to rank as the ninth busiest in the U.S., the Port of Seattle said Thursday.

Sea-Tac previously ranked as the 13th busiest airport in the country.

In 2016, Sea-Tac passenger traffic hit a record level for the sixth year in a row. The airport served 45.7 million passengers, 3.4 million more than in 2015.

The 8 percent passenger growth rate is Sea-Tac’s second largest in the past two decades, topped only by 2015’s 12.9 percent increase.

Almost 4.9 million international passengers traveled through Sea-Tac last year, up 11.1 percent from 2015.

That figure was boosted when two new international airlines started service into Sea-Tac in 2016 — Volaris out of Guadalajara, Mexico, and Xiamen out of Shenzhen, China.

The Port said Sea-Tac airport supports more than 109,000 direct jobs.

That includes 18,500 people working at the airport, plus tens of thousands more in airline services, freight transportation, construction or tourism.

Katherine Kertzman, chief executive of Seattle Southside Regional Tourism Authority, described the airport as “an economic engine for our region” and said the growth is spurring construction of more than 1,200 new hotel rooms in the southside area by the end of 2018.

To accommodate the airport’s continuing growth, the Port is investing more than $2 billion in capital-improvement projects.

Those include the $550 million North Satellite modernization project, a new $660 million International Arrivals Facility and a new baggage-handling system.

These projects will add more gates to the airport and more than double dining and retail outlets at the North Satellite, which is used exclusively by Alaska Air. And international travelers will have a direct connection to the terminal and more baggage and passport services.