U.S. Route 12 in Washington - Route Description

Route Description

U.S. Route 12 begins in Aberdeen on a pair of one-way streets, Heron Street eastbound and Wishkah Street westbound. At its western terminus, US 12 intersects US 101, which goes west along Heron and Wishkah, and south across Grays Harbor to the south side of Aberdeen. The eastbound and westbound lanes of US 12 merge just east of the Wishkah River, near the Grays Harbor Historic Seaport. US 12 then leaves Aberdeen to the east along the Chehalis River, where it passes through the towns of Central Park and Montesano. Between Aberdeen and Elma, US 12 is four lanes wide. The majority of the highway in Washington, however, is a rural two-lane road.

In the town of Elma, US 12 exits the highway at a diamond interchange. From there, the main highway continues east to Olympia as State Route 8 (SR 8), and US 12 heads southeast towards Oakville and Rochester. East of Oakville, US 12 runs north of the Chehalis Indian Reservation. It then continues east through the town of Rochester, and interchanges with I-5 at exit 88 in the town of Grand Mound.

US 12 continues south concurrent with I-5 through Chehalis and Centralia before exiting again at exit 68 south of Napavine. The highway then heads east along the Cowlitz River and passes through the town of Mossyrock, where it intersects SR 122. East of Mossyrock, US 12 runs just north of Mossyrock Dam and Riffe Lake. In the town of Morton, it intersects SR 7, which heads north to Tacoma. It then ascends the Cascade Range, passing south of Mount Rainier, and intersects SR 123, which serves the Stevens Canyon entrance of Mount Rainier National Park. Twelve miles (19 km) east of this intersection, US 12 crosses the Cascades over White Pass at an elevation of 4,500 feet (1,372 m). White Pass is the only crossing of the Cascades open year-round between I-90 over Snoqualmie Pass and SR 14 through the Columbia River Gorge.

After it descends the mountains, US 12 intersects SR 410 (formerly US 410) west of Naches, which serves Chinook Pass, Cayuse Pass, and the White River entrance of Mount Rainier National Park. East of Naches, US 12 widens once again to four lanes as it approaches the city of Yakima. There, it has an interchange with I-82 and US 97 at exit 31. US 12 then runs concurrently with I-82, bypassing the towns of Toppenish and Prosser and paralleling the Yakima River, until exit 102 near the Tri-Cities. At exit 102, it meets the western terminus of Interstate 182. US 12 and I-182 then run concurrently east through the Tri-Cites. In Pasco, I-182 ends, and US 12 intersects US 395.

US 12 then heads south to the town of Wallula, intersecting US 730, then east to Walla Walla, north to Dodge, and east to Clarkston before crossing the Idaho state line over the Snake River just outside of Lewiston. US 12 through Walla Walla consists of a four-lane bypass, also known as Inland Empire Highway. The alignment of US 12 through Walla Walla County passes by a number of historical landmarks, such as Whitman Mission and Fort Walla Walla.