Legislative action in 2007 named I-5, I-82 and I-90 “Green Highways.” With this designation, these routes through Washington have been identified as routes to provide locations for alternative fuel facilities.

The Washington State Legislature funded the signs in House Bill 1094, which states: "If the "Green Highway" provisions of Engrossed Second Substitute House Bill No. 1303 (cleaner energy) are enacted, the department shall erect signs on the interstate highways included in these provisions noting that these interstates have been designated "Washington Green Highways."

House Bill 1303 : "The legislature finds that excessive dependence on fossil fuels jeopardizes Washington's economic security, environmental integrity, and public health. Finally, the legislature finds that to reduce fossil fuel dependence, build our clean energy economy, and reduce climate impacts, the state should develop policies and incentives that help businesses, consumers, and farmers gain greater access to affordable clean fuels and vehicles and to produce clean fuels in the state."

The West Coast Green Highway is the 1,350 miles of Interstate 5 (I-5) stretching from the U.S. border with Canada, through Washington, Oregon, and California, to the U.S. border with Mexico. Designated a “Corridor of the Future” by the U.S. Department of Transportation, I-5 could soon become the nation’s cleanest, greenest, and smartest highway. The drivers of hundreds of thousands of cars and trucks that travel on this major roadway each day soon may select from a menu of clean alternative fuel such as natural gas, biodiesel, ethanol, or hydrogen. Learn more about the West Coast Green Highway Project.