List of Interstate Highways in Washington

Markers for I-5, I-90, and I-405
Map of Washington's highways with the Interstates in red
System information
Length:	764.27 mi (1,229.97 km)
Highway names
Interstates:	Interstate X (I-X)
US Highways:	U.S. Route X (US X)
State:	State Route X (SR X)
System links
State highways in Washington Interstate US State Scenic Former PSH 1964 renumbering Former

In the U.S. state of Washington, there are seven roads that are part of the Interstate Highway System, three primary routes and four auxiliary routes, spanning 764.27 miles (1,229.97 km).^{[n 1]} These highways connect every city in the state with a population of over 100,000 (Seattle, Spokane, Tacoma, Vancouver, Bellevue, and Everett)^[1] as well as the state capital, Olympia.

Interstate 90 (I-90) is the longest primary Interstate Highway in Washington, which connects Seattle to Spokane and the Idaho border, measuring 297.52 mi (478.81 km), while I-82, connecting the Oregon border city of Umatilla to Elensburg via Yakima, is the shortest at 132.57 mi (213.35 km). The longest auxiliary Interstate Highway in Washington is I-405, a bypass of Seattle through the eastside, at 30.30 mi (48.76 km), and the shortest is I-705, a spur into downtown Tacoma, at 1.50 mi (2.41 km). One route, I-605, has been proposed over the years to form another eastside bypass, however there are no plans to construct this fifth auxiliary route.

Primary Interstate Highways

Interstate 5 in Seattle

After passage of the Federal Aid Highway Act of 1956, which formed the Interstate Highway System,^[2] the American Association of State Highway Officials had approved I-5 and I-90 across Washington on August 17, 1957.^[3] I-82 was approved on October 17, 1957, two months after I-5 and I-90,^[4] as part of a 1,102-mile-long (1,773 km) addition to the Interstate Highway System.^[5]

Number	Length (mi)[6]	Length (km)	Southern or western terminus	Northern or eastern terminus	Formed	Removed
I‑5	276.62	445.18	I-5 at the Oregon state line	BC 99 at the Canada–United States border	1957	current
I‑82	132.57	213.35	I‑90 in Ellensburg	I-82 at the Oregon state line	1957	current
I‑90	297.52	478.81	SR 519 in Seattle	I-90 at the Idaho state line	1957	current

Auxiliary Interstate Highways

I-182 in Richland

I-205 and I-405 were first codified into Washington State Law in 1970,^[7][8] and I-182 and I-705 were codified in 1979.^[9][10]

I-705 was completed in 1990,^[11] after a series of federal budget cuts,^[12] and was the last Interstate Highway to be completed in the state of Washington.^[13]

Number	Length (mi)[6]	Length (km)	Southern or western terminus	Northern or eastern terminus	Formed	Removed
I‑182	15.19	24.45	I‑82 / US 12 near Richland	US 12 / US 395 in Pasco	c. 1972	current
I‑205	10.57	17.01	I-205 at the Oregon state line	I‑5 in Salmon Creek	c. 1975	current
I‑405	30.30	48.76	I‑5 / SR 518 in Tukwila	I‑5 / SR 525 in Lynnwood	1964	current
I‑605	—	—	To be determined	To be determined	proposed	—
I‑705	1.50	2.41	I‑5 / SR 7 in Tacoma	Schuster Parkway in Tacoma	1990	current
Future

See also

• Washington Roads portal
• Washington portal

Footnotes

Notes

1. The mileage is a sum of the lengths listed and cited on this page.

References

1. Staff (2010). Census Redistricting Data (Public Law 94-171) Summary File (Zip) (Report). Washington State Office of Financial Management and U.S. Census Bureau. Retrieved December 24, 2013.
2. Lewis, Tom (1997). Divided Highways: Building the Interstate Highways, Transforming American Life. New York: Viking. pp. 120–1, 136–7. ISBN 0-670-86627-X.
3. Official Route Numbering for the National System of Interstate and Defense Highways as Adopted by the American Association of State Highway Officials (Map). Scale not given. Cartography by Public Roads Administration. Public Roads Administration. August 14, 1957. Retrieved January 20, 2014.
4. Routes to be Added to the National System of Interstate and Defense Highways (Map). Scale not given. Cartography by Public Roads Administration. Public Roads Administration. October 17, 1957. Retrieved January 20, 2014.
5. Mooney, Richard E. (October 19, 1957). "1,102 Miles Added To U.S. Roads Plan". The New York Times. p. 1. Retrieved 20 January 2014 – via ProQuest. (subscription required (help)).
6. Finch, Mark (2012). State Highway Log: SR 2 to SR 971 (PDF) (Report). Washington State Department of Transportation. Retrieved January 2, 2014.
7. "47.17.400: State route No. 205". Revised Code of Washington. Washington State Legislature. 1970. Retrieved January 20, 2014.
8. "47.17.595: State route No. 405". Revised Code of Washington. Washington State Legislature. 1970. Retrieved January 20, 2014.
9. "47.17.372: State route No. 182". Revised Code of Washington. Washington State Legislature. 1979. Retrieved January 20, 2014.
10. "47.17.819: State route No. 705". Revised Code of Washington. Washington State Legislature. 1979. Retrieved January 20, 2014.
11. Virgin, Bill (October 26, 2006). "At 50, interstates feeling their age". Seattle Post-Intelligencer. Hearst Corporation.
12. Harper, Robert (April 16, 1980). "12 State Road Projects Budget Casualties". The Spokesman-Review. Spokane, Washington: Cowles Publishing Company. p. A2. Retrieved January 8, 2011.
13. Nelson, Robert T. (March 29, 1998). "In the 6th District, Dicks Keeps Delivering". The Seattle Times. Retrieved January 8, 2011.

External links

• Washington State Department of Transportation
• Washington highways on AARoads