The route connects Elma and Olympia as part of a corridor between Aberdeen and the Puget Sound region.

After passing Downtown McCleary, SR 8 has a partial cloverleaf interchange with Mox Chehalis Road.

From the interchange, the expressway goes east to form the northern boundary of the Capitol State Forest,[8] and passes Summit Lake.

When combined with US 12 to the west and US 101 to the east, it serves as the primary connection between the Puget Sound region and Washington's Pacific coast.

Before the Primary and Secondary system, SR 8 in 1923 was part of a branch of State Road 9, from Elma to Grand Mound.

[13][14] The highway became part of the Ocean Freeway, an expressway that aimed to connect Aberdeen and the Pacific Coast with Olympia in the 1960s.