Washington State Route 527

State Route 527 (SR 527, also known as the Bothell–Everett Highway) is a state highway in Snohomish County, Washington. It travels 9 miles (14 km) from north to south, connecting the northern Seattle suburbs of Bothell, Mill Creek, and Everett. The highway intersects Interstate 405 (I-405) at its southern terminus, SR 96 in northern Mill Creek, and I-5 at an interchange with SR 99 and SR 526 in Everett.

The Bothell–Everett Highway was built in the 1910s as part of the intercity Pacific Highway and briefly formed part of U.S. Route 99 (US 99) in 1926. The following year, US 99 was moved west to a new highway that would later become modern-day SR 99. The old route to the east was signed by the state as Secondary State Highway 2A (SSH 2A) from 1937 to 1943 and SSH 2J from 1957 to 1964, when it was renumbered as SR 527.

Since its opening, suburban development in Mill Creek and northern Bothell has contributed to traffic congestion on stretches of SR 527. During the 1990s and early 2000s, the state government funded several projects that widened the highway to its present four-lane configuration with sidewalks, bus pullouts, and bicycle lanes. The southernmost 2.5 miles (4.0 km) of the highway, from SR 522 to I-405, was transferred to the Bothell city government in 2011 and decommissioned from the state highway system.

SR 527 begins as a continuation of the Bothell–Everett Highway at a partial cloverleaf interchange with I-405 in northern Bothell, located in Snohomish County. The interchange is located adjacent to the Canyon Park park and ride, a major bus transfer facility. The highway travels northeast through the Canyon Park business park and turns north after crossing North Creek, following it to a junction with SR 524 at Thrasher's Corner. SR 527 then crosses into the unincorporated North Creek area, which is filled with suburban homes and apartment complexes that line the road, along with commercial areas at Kennard Corner and near North Creek County Park.

The highway continues north into the center of Mill Creek at a junction with 164th Street Southeast. Through central Mill Creek, SR 527 forms the border between the Mill Creek Town Center, a lifestyle center that runs to the west along North Creek, and the city's suburban neighborhoods to the east. Near Henry M. Jackson High School, the highway turns northeast and intersects SR 96 at Murphy's Corner, located at the southern city limit of Everett. The intersection has limited turns due to the acute angle at which SR 527 enters from the south; an auxiliary street to the west (16th Avenue SE) is used to access southbound SR 527 from the west side of SR 96.

Following the junction, SR 527 curves along the shore of Silver Lake, passing two small parks. The highway briefly travels west along the northeast shore of the lake before turning sharply to the north onto 19th Avenue Southeast and passes through a commercial district while remaining parallel to I-5. Near the Eastmont park and ride, SR 527 intersects I-5 and crosses over the freeway to its terminus, a junction with SR 99, Broadway, and part of SR 526 (the Boeing Freeway). The highways connect SR 527 to Downtown Everett, the Everett Mall area, and the Boeing Assembly Plant, respectively.

SR 527 is maintained by the Washington State Department of Transportation (WSDOT), which conducts an annual survey on state highways to measure traffic volume in terms of annual average daily traffic. Average traffic volumes on the highway in 2016 ranged from a minimum of 19,000 vehicles in northern Mill Creek to a maximum of 54,000 vehicles at the I-405 interchange. The highway is generally four lanes wide with a landscaped median or center turn lane in some areas. The entire route is designated as part of the National Highway System, a network of roads identified as important to the national economy, defense, and mobility. The corridor is also served by buses operated by Everett Transit and Community Transit, including the Swift Green Line—a bus rapid transit route that began service in 2019 and runs every 10–20 minutes between stations on SR 527 with transit signal priority and other features.

An early wagon road along North Creek between Bothell and Lowell (now part of Everett) was built in the late 19th century by local settlers and the county government. The road was graded and improved with a permanent (but unpaved) surface in the early 1910s using funds allocated by the state government. It was incorporated into the state highway system in 1913 as part of the Pacific Highway, the primary cross-state route in Western Washington. The Bothell–Everett portion of the highway was paved with concrete in 1916, following a bond issue for improved roads approved by Snohomish County voters the year prior. It cost $183,750 to construct the 14.5-mile (23.3 km) section.