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 urban loop is the most direct route to Redmond, home of Microsoft, via the freeway along State Route 520. As a result of growth in the greater Seattle area, Interstate 405 carries significant traffic volume, almost on a level like I-405 in California, albeit with fewer lanes.
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 as I-405 with its completion by 1971.2