Interstate 605 (Washington)

Interstate 605
Interstate 605
	Proposed 1998 corridor of I-605 highlighted in red
Route information
	Auxiliary route of I-5
Status	Never built
NHS	Entire route
Location
Country	United States
State	Washington
Highway system
	Interstate Highway System; Main; Auxiliary; Suffixed; Business; Future; State highways in Washington; Interstate; US; State; Scenic; Pre-1964; 1964 renumbering; Former;

Interstate 605 (I-605) is the popular moniker given to several proposals for a new auxiliary Interstate Highway bypassing I-5 and I-405 in the U.S. state of Washington. Proposals have been heard from since the 1960s, including highways connecting from I-5 all the way to the Canada–US border, and some just between I-5 and I-90. The Washington State Department of Transportation (WSDOT) has no projects designated I-605 at this time. However, some I-605 proposals have included State Route 18, which has been partially constructed as a freeway.