State Route 140 (SR 140) originated as 15th Street at an intersection with SR 14 in Washougal, located about 1.47 miles (2.37 km) east of the eastern terminus of SR 500 on the shoreline of the Columbia River. 15th Street traveled north through Downtown, crossing the Vancouver–White Salmon rail route of the BNSF Railway and intersecting the former alignment of SR 14, E Street, before turning northeastward onto 17th Street. The highway crossed the Washougal River out of Washougal in a large forest and became the Washougal River Road. The roadway paralleled the river northeast and later east into the forests and mountains of Skamania County until the river turned north. SR 140, renamed Canyon Creek Road, turned southeast and encountered a series of sharp turns until terminating at SR 14 in Prindle.
A 1949 map of the Vancouver area featuring Secondary State Highway 8B (SSH 8B), the early predecessor to SR 120 and SR 140 that was designated between 1937 and 1964.
SR 140 began as Canyon Creek Road and first appeared on a map in 1911. The first numbered highway on the road was Secondary State Highway 8B (SSH 8B), established in 1937. The roadway traveled along the Washougal River and Canyon Creek between Primary State Highway 8 (PSH 8), co-signed as U.S. Route 830 (US 830), between Washougal and Prindle. SSH 8B remained unchanged until the 1964 highway renumbering, when the route was renumbered as State Route 120 and PSH 8 became State Route 12. After US 12 was extended west across Washington in 1967, SR 12 became SR 14 and SR 120 became SR 140. In 1968, US 830 was deleted and SR 14 was realigned south onto a newer alignment. In 1992, SR 140 was removed from the state highway system.
^Washington State Legislature (18 March 1937). "Chapter 207: Classification of Public Highways". Session Laws of the State of Washington. Session Laws of the State of Washington (1937 edition ed.). Olympia, Washington: Washington State Legislature. p. 1005. Retrieved 28 September 2009. (b) Secondary State Highway No. 8B; beginning at Washougal on Primary State Highway No. 8, thence in a northerly and easterly direction by the most feasible route following the general course of the Washougal river to a junction with Primary State Highway No. 8 east of Washougal.