Cornelius Pass Road begins at an intersection with Southeast Blanton Street in southern Hillsboro, about one block south of the Tualatin Valley Highway. It travels north across a set of railroad tracks and intersects OR 8 before continuing into Hillsboro's suburban neighborhoods. The street passes under a viaduct carrying light rail trains on the Blue Line near Quatama station near the Orenco Woods Nature Park. From the undercrossing, the highway travels through several business parks on the east side of Intel's main factory, connected by the intersecting Cornell Road and Evergreen Parkway. Cornelius Pass Road then reaches an interchange with U.S. Route 26 and turns northeast as it leaves Hillsboro. The highway winds its way around farms and forestland as it ascends into the Tualatin Mountains, reaching its highest point at Cornelius Pass, elevation. The narrow road then descends from the mountains along McCarthy Creek and approaches the Multnomah Channel of the Columbia River, terminating at an intersection with U.S. Route 30 northwest of Portland. Cornelius Pass is one of only two main north–south connecting roads in Hillsboro. The former country road handles 11,000 drivers each day and is an arterial route from the Tualatin Valley between Hillsboro to the Columbia River north of Portland. A mountainous road at points, 1,500 of the 11,000 vehicles each day are tractor-trailers on the road designed to handle up to 10,000 vehicles per day. A portion of the road, from US 26 to Cornell, is part of the National Highway System. As of 2010, the average daily traffic on the road in Washington County from north to south was 8,130 vehicles just north of Germantown Road, 11,003 just south of Germantown, 17,947 a little south of West Union Road, 38,860 just north of Imbrie Drive, 26,542 just north of Cornell Road, 18,863 a bit north of Quatama Road, 18,208 just north of Baseline Road, 21,156 a little south of Baseline, and 16,294 just north of the road's terminus, until 2018, at Tualatin Valley Highway.
History
The road was built by Thomas R. Cornelius in the 19th century. The interchange with the Sunset Highway was rebuilt and widened in 1989, and the road widened to five lanes from the freeway to Cornell Road the following year. In 1996, the road was extended southward when 216th and 219th avenues were renamed and became the southern section of the road, terminating at Tualatin Valley Highway. At that time, the intersection with Baseline Road was re-aligned, but most of the extension was simply a renaming of 216th Avenue. The intersection with US 26 was altered in 2005 with new on- and off-ramps extending from Cornelius Pass to the east, where a railroad overpass had previously been located. In 2008, the entire Multnomah County section was changed to a no-passing zone on the winding road over the Tualatin Mountains. A one-mile section from Lois to Wilkins streets closed for eight months in 2010 in order to widen the road in that area to five lanes as well as add bike lanes and sidewalks. The $12 million project included a new bridge over Beaverton Creek. The county hoped to widen the remaining portion of the road to five lanes between Walbridge/Aloclek and Wilkins. Announced in 2011, the expected cost was $10.1 million and would include a new bridge over Rock Creek. Construction closed the section for six months, with the new bridge opening on December 31, 2012; at that time, the remaining widening was expected to continue until the middle of 2013. Hillsboro also began preliminary work in 2011 to extend Cornelius Pass south of Tualatin Valley Highway to prepare for the development of South Hillsboro. The Oregon Legislature approved $9.5 million in 2012 to fund safety improvements such as guardrails. Hillsboro also announced plans in 2012 to widen the road to seven lanes between Cornell and US 26. The widening project was completed in March 2017 at a total cost of $18.3 million. Construction began in 2016 on the extension of Cornelius Pass Road south of Tualatin Valley Highway. The extension, approximately one-third of a mile long, was opened to traffic in July 2018. The new section crosses Portland & Western Railroad tracks and takes Cornelius Pass Road into the under-construction South Hillsboro area. The street currently ends at its intersection with an also-newly built section of SE Blanton Street. In July 2019, a five-mile stretch of Cornelius Pass Road between US 30 and NW Germantown Road began an 11-week closure. This stretch of road had experienced a high rate of crashes in preceding years, and Multnomah County closed the road so that safety improvements could be carried out, including curve realignment and widening of shoulders.
