Interstate 405 north at Downtown Bellevue, Washington. 06/27/15
Interstate 405 provides a bypass to the east of Seattle, connecting with several major suburbs on the east shore of Lake Washington. The freeway is the most direct route to Redmond, home of Microsoft, via the Washington 520 freeway. As a result of growth in the greater Seattle area, Interstate 405 carries significant traffic volume, almost on a level like its sibling in California, albeit with fewer lanes. To alleviate some of this congestion, a second north-south freeway is being considered for the eastern suburbs of Seattle, dubbed as Interstate 605 by some. It remains unclear if this new highway will be constructed.
Interstate 405 is part of High Priority Corridor 35: FAST Corridor.
The original proposal for Interstate 405 around greater Seattle was submitted to the American Association of State Highway Officials (AASHO) in a letter dated July 14, 1958.1 Initial stretches were designated as Washington State Route 405 between Renton and Tukwilla. The first section opened to traffic in September 1965. SR 405 was redesignated I-405 with its completion by 1971.2