Costco update Representatives of Costco met with city of Tumwater officials this week about a proposal to open a new 160,000-square-foot store at the corner of Tumwater Boulevard and Interstate 5.

Costco stores in WA Costco, which is headquartered in Washington, has 34 locations across the state, according to its website. Costco’s Bellingham store is located at 4125 Arctic Ave.