The highway traveled south from its current western terminus until the construction of a new interchange with I-5 in 2008, part of a project to widen SR 502 and install a median barrier on the roadway.[4] The four-lane highway travels east through rural Clark County and the community of Dollars Corner before it enters the city of Battle Ground, where it becomes Main Street.[9] SSH 1S was created in 1937 during the formation of the primary and secondary state highways,[10] traveling on a 57.60-mile-long (92.70 km) route east from Primary State Highway 1 (PSH 1) and U.S. Route 99 (US 99) north of Mount Vista to intersect SSH 1U in Battle Ground and turned north towards Amboy and west to end at PSH 1 and US 99 in Woodland.[1] During construction of the interchange, WSDOT uncovered archaeological remains belonging to a Coast Salish settlement at Gee Creek that were at least 8,000 years old.[21] The new, four-lane highway, which includes 10-foot (3.0 m) shoulders for bicycle and pedestrian travel and traffic signals at major intersections, opened on June 27, 2016.