From Darrington take state Route 530 west. The highway passes scattered homes and farms. There are great views of Whitehorse Mountain off to the south across lush pasturelands. Its flanks host some of the lowest-elevation glaciers in the 48 states. The highway follows the north fork of Stillaguamish River, passing a string of almost-forgotten hamlets, former stations on the now-abandoned railway.
The community of Oso was settled as Allen in the 1880s. The name was changed to the Spanish word for “bear” in the 1890s to avoid confusion with the Mason County town of Allyn. On March 22, 2014, a rain-soaked mountainside north of the river collapsed. A slide of mud and debris buried the highway and temporarily blocked the river. Forty-three people lost their lives in the disaster. Highway 530 had to be rebuilt and raised to 20 feet in some sections. The road later reopened in 2014.
Arlington (population 22,041) stands just below the confluence of the north and south forks of the Stillaguamish. Settlers homesteaded on the rich valley soils in the early 1860s. Railroads arrived in the 1880s and a station was established under the name of Haller City. An adjacent town site was also platted as Arlington, named for the national cemetery near Washington, D.C.
Residents voted to consolidate the two settlements under the name Arlington in 1903. The town prospered as a lumbering center and once ranked among the top producers of shingles. The Stillaguamish Valley Pioneer Museum has exhibits on the history of this period.
Highway 530 leads 3 miles west through farmland to busy Interstate 5. Just east of I-5 exit 206 is Arlington Airport, a busy general aviation field. The airport was a World War II-era Naval Auxiliary Air Station and hosts a nationally-renowned experimental aircraft fly-in each summer.
Back on I-5 continue south to Marysville (population 71,681), a former trading post founded in 1878 on a branch of the Snohomish River known as the Ebey Slough. Marysville preserves the Gehl Pioneer Home, built with hand-hewn cedar in 1884, in Jennings Memorial Park.
The city celebrates its agricultural roots with the annual Strawberry Festival each June. Adjoining Marysville on the west is the Tulalip Indian Reservation, which was established by treaty in 1855. It is also the site of the earliest Roman Catholic mission on Puget Sound, established in 1857.
Just west of I-5 exit 200 the Tulalip Resort Casino beckons gamblers. Quil Ceda Village, located on the tribe’s business park just west of I-5 exit 202, is the state’s first municipality organized and administered by Native Americans. Just west of I-5 exit 202, Seattle Premium Outlets beckons shoppers with more than 100 outlet stores.
Just south of Marysville I-5 bridges Ebey Slough then traverses the floodplain of the Snohomish River. Dikes and levees protect the fertile farmland from regular flooding, although some of this lowland country is usually under water each winter. The freeway rises to span the Snohomish River and we’re back in Everett where our Mountain Loop tour began.
– Written by John King, and last updated in November 2022.
–Top image of Cascade Mountains seen from Darrington. Photo by Cavan Images/Getty Images