Seattle-Tacoma International Airport is one of the major airports of the Pacific Northwest and the main gateway to Alaska (consequently a major hub for Alaska Airlines). The airport is growing and is also moving closer to a major Terminal C expansion. Seattle Airport offers plenty of lounges for passengers waiting for their flights and connections. Most of these airport lounges are limited to those holding elite memberships and/or flight tickets with associated airlines, but some are open to anyone for a fee. Some airport lounges cater to a particular type of traveler (such as the USO Center catering to active duty military personnel).