I-5 also has three related auxiliary Interstates in the state, I-205, I-405, and I-705, as well as several designated business routes and state routes. Most of the freeway is four lanes in rural areas and six to eight lanes in suburban areas, including a set of high-occupancy vehicle lanes in the latter. The segment in Downtown Seattle is also among the widest freeways in the United States, at 13 lanes, and includes a set of express lanes that reverse direction depending on time of the day. I-5 is the only interstate to traverse the whole state from north to south and is Washington's busiest highway, with an average of 274,000 vehicles traveling on it through Downtown Seattle on a typical day. Within the Seattle metropolitan area, the freeway connects the cities of Tacoma, Seattle, and Everett. It spans 277 miles (446 km) across the state of Washington, from the Oregon state border at Vancouver, through the Puget Sound region, to the Canadian border at Blaine. Interstate 5 ( I-5) is an Interstate Highway on the West Coast of the United States that serves as the region's primary north–south route.

Clark, Cowlitz, Lewis, Thurston, Pierce, King, Snohomish, Skagit, Whatcom

Interstate 5 to barona casino