 The highway was co-signed with State Road 10 from Wenatchee to the border.State Road 10 was relocated to its original alignment on the west side of the Columbia River, which had been improved with oiled macadam surfacing, and was later signed as Primary State Highway 10 (PSH 10) in the 1937 reformation of the state highway system.By the end of the 1930s, the entirety of US 97 and PSH 10 had been paved in concrete and asphalt.