When the current state highway numbering system was first posted in 1964, SR 120 started at Jct US 830 in Washougal and headed north, then east, along the Washougal River, turning south and returning to US 830 about 10 miles east of Washougal. When US 12 was extended into Washington State in 1967, SR 120 was renumbered SR 140. Effective April 1, 1992, SR 140 was dropped from the state highway system.
Before 1964, SR 120 had been SSH 8B.
Primary State Hwys Secondary State Hwys