Title: Interstate 5 in Washington - Wikipedia
Headings: Interstate 5 in Washington
Interstate 5 in Washington
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Contents
Route description
Southwestern Washington
South Sound region
Seattle and Shoreline
Snohomish County
Skagit and Whatcom counties
Seattle express lanes
Express lane exit list
History
Early state and national highways
State upgrades and Interstate planning
Suburban and rural construction
Seattle planning and construction
Major projects and expansions
Incidents and closures
Future projects and proposals
Exit list
References
External links

Content: 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. The freeway follows several historic railroads and wagon trails developed during American settlement of western Washington in the mid-to-late 19th century. The state legislature incorporated local roads into the Pacific Highway in 1913, connecting the state's southern and northern borders between Vancouver and Blaine. The Pacific Highway was built and paved over the next decade, and became the northernmost segment of the national U.S. Route 99 (US 99) in 1926. The federal government endorsed the creation of a national expressway system in the 1940s, including several bypasses on US 99 that were built by the state in the early 1950s. The state's planned toll superhighway in the Seattle area was shelved in favor of a federally-funded freeway under the new Interstate Highway System, under which I-5 was created in 1957. Construction of I-5 was completed in 1969, and several segments of the highway have been widened or improved in the decades since. Contents
1 Route description
1.1 Southwestern Washington
1.2 South Sound region
1.3 Seattle and Shoreline
1.4 Snohomish County
1.5 Skagit and Whatcom counties
2 Seattle express lanes
2.1 Express lane exit list
3 History
3.1 Early state and national highways
3.2 State upgrades and Interstate planning
3.3 Suburban and rural construction
3.4 Seattle planning and construction
3.5 Major projects and expansions
3.6 Incidents and closures
3.7 Future projects and proposals
4 Exit list
5 References
6 External links
Route description
Interstate 5 is the only Interstate to traverse Washington from north to south, serving as the primary highway for the western portion of the state. It is listed as part of the National Highway System and the state's Highways of Statewide Significance program, recognizing its connection to major communities. I-5 has three auxiliary Interstate Highways within Washington: