Why have so many huge hotels inexplicably popped up around Anchorage in recent years?

Perhaps it hasn't been quite so sudden, or I'm just super unobservant, or I only notice now that I drive C Street every day. But from what I understand, tourism in Alaska has been in decline the last few years, and I've yet to identify another industry that requires huge amounts of temporary lodgings.

Here's what I mean:

• The Fairfield Suites and Motel 6 right next to each other on C Street and International.
• Homewood Suites (Hilton, two large buildings), Hampton Inn around C Street and Tudor.
• The (weird) Dimond Center Hotel in the Dimond Mall parking lot.