State Route 31 (SR 31) is a Washington state highway located entirely in Pend Oreille County. The highway, which is long, starts at an intersection with in Tiger and travels north to the Canada–US border north of Metaline Falls. At the border, SR 31 becomes (BC 6). The route parallels the Pend Oreille River for most of its route and the primary functions of the highway is to serve and connect Tiger, Ione, Metaline and Metaline Falls with British Columbia. Before 1964, the route from Newport to BC 6 was the northernmost section of , which ran from Spokane to BC 6. Originally created in 1964, SR 31 extended southeast to an intersection with (US 2, formerly ) in Newport. The North Cascades Highway (SR 20) was extended to Newport in 1973 and SR 31 from Newport to Tiger became SR 20. SR 31 had one auxiliary route, , which became SR 211 after SR 20 was extended. Route description State Route 31 (SR 31) is long within Pend Oreille County, Washington from in Tiger north to (BC 6) at the Canada–US border, located north of Metaline Falls. The highway parallels the Pend Oreille River for most of its route and connects Tiger, Ione, Metaline and Metaline Falls with British Columbia. The route also parallels the Pend Oreille Valley Railroad from Tiger to Metaline Falls; the railroad extends south to Newport along SR 20 and east to Dover, Idaho. SR 31 starts at an intersection with SR 20 and Tiger East Road in the small community of Tiger. The road turns northwest after the intersection and then curves north after intersecting Vogel Road. After crossing the railroad, the highway forms the eastern boundary of Ione Municipal Airport and later passes Sullivan Lake Road. At the Sullivan Lake Road junction, SR 31 is named McKay Road and crosses the Ione Millpond to enter the city of Ione. There, the route is renamed Second Street and leaves the city to parallel the Pend Oreille Valley Railroad and the shoreline of the Pend Oreille River. The name of the road changes to Lehigh Avenue, a name that stays with SR 31 until the Canada–US border. The railroad crosses the road and later bridges the Pend Oreille River, as the highway turns northwest and reverts northeast. The route reaches Metaline and curves southeast to cross the Pend Oreille River on the Pend Oreille Bridge