High Quality Content by WIKIPEDIA articles! State Route 251 (SR 251, now Northport–Boundary Road) is a former 10.86-mile (17.48 km) long state highway in Stevens County, Washington. The highway began at SR 25 in Northport and continued northeast parallel to the Columbia River to Boundary, an unincorporated community, where it crossed the Canada – United States border into British Columbia as British Columbia Highway 22A. SR 251 was originally a county road until 1913, when it was added to the state highway system, but was later removed. The roadway was re-added as an extension to an already existing state highway. In 1937, it was reclassified as a secondary highway named Secondary State Highway 22A (SSH 22A) until 1964, when it became SR 251. In 1984, control of the road was relinquished by the state to Stevens County and it was renamed Northport–Boundary Road.