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Interstate 5 (Washington)

Interstate 5 marker

Interstate 5
Interstate 5 is highlighted in red
Route information
Defined by RCW 47.17.020
Maintained by WSDOT
Length: 276.62 mi (445.18 km)
Existed: August 7, 1947 by FHWA
1956 – present
Tourist
routes:
Lewis and Clark Highway (from Vancouver to SR-4 near Longview)
Major junctions
South end: I-5 at the Oregon state line
  SR 14 in Vancouver
I‑205 in Salmon Creek
US 12 near Centralia
US 101 in Tumwater
I‑705 in Tacoma
I‑90 in Seattle
US 2 in Everett
SR 20 in Burlington
North end: BC 99 at Canada–United States border in Blaine
Location
Counties: Clark, Cowlitz, Lewis, Thurston, Pierce, King, Snohomish, Skagit, Whatcom
Highway system
SR 4 SR 6

Interstate 5 marker

Interstate 5 in Washington (I-5) is a 276.62-mile (445.18 km) highway in the U.S. state of Washington that extends from its border with Oregon to its border with Canada. Serving the cities of Vancouver, Kelso, Chehalis, Centralia, Olympia, Tacoma, Seattle, Everett, Mount Vernon, and Bellingham, it is the main route between Portland, Oregon, and Vancouver, British Columbia.

It is the only interstate to traverse the whole north–south length of Washington, but the undivided highways U.S. Route 97 and U.S. Route 395 do also. I-5 is also the only north–south primary interstate highway in Washington. The road is the busiest in the state; an estimated 240,000 motorists use the road daily. The second busiest is I-405 at 201,000.

I-5 enters Washington at the Interstate Bridge over the Columbia River between Portland and Vancouver. It initially heads north through Vancouver and intersects SR 14, the first segment of SR 501, and SR 500 until the interchange with I-205 in Salmon Creek, where the freeway begins a turn to the northeast. I-5 closely follows the alignment of old U.S. Route 99, and in some locations the US 99 alignment has become I-5. The interstate passes the Vancouver branch of Washington State University. Southeast of Ridgefield, the highway intersects SR 502 and the second segment of SR 501 before continuing north along the Columbia River to Woodland.


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