The 2.30-mile (3.70 km) long route runs north from U.S. Route 12 (US 12) in Clarkston to cross the Snake River and turn east after intersecting SR 193 to terminate at State Highway 128 (SH 128) on the Idaho state line.

[6][7] SR 128 after the US 12 intersection was used by 5,000 motorists daily in 2007 based on annual average daily traffic (AADT) data collected by the Washington State Department of Transportation.

[9] The road ran from Pomeroy in Garfield County southeast to Peola and later northeast to Clarkston, terminating at Primary State Highway 3 (PSH 3), co-signed with U.S. Route 410 (US 410) at both termini.

[13][14] A year later, SR 128 was truncated from Pomeroy to Clarkston along its current route,[15] a loss of 42.19 miles (67.90 km) in total.

[12] The transfer was estimated to cost the county government $250,000 for maintenance, due in part to 1 mile (1.6 km) of new pavement required near Peola.