With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: South America is an isthmus.
text_B: State Route 31 -LRB- SR 31 -RRB- is a Washington state highway located entirely in Pend Oreille County .. Pend Oreille. Pend Oreille County, Washington. Washington state highway. State highways in Washington. Pend Oreille County. Pend Oreille County, Washington. The highway , which is 26.79 mi long , starts at an intersection with in Tiger and travels north to the Canada -- US border north of Metaline Falls .. Tiger. Tiger, Washington. Metaline Falls. Metaline Falls, Washington. Metaline. Metaline, Washington. At the border , SR 31 becomes -LRB- BC 6 -RRB- .. 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 .. Tiger. Tiger, Washington. Metaline Falls. Metaline Falls, Washington. Pend Oreille. Pend Oreille County, Washington. Pend Oreille River. Pend Oreille River. Ione. Ione, Washington. Metaline. Metaline, Washington. British Columbia. British Columbia. Before 1964 , the route from Newport to BC 6 was the northernmost section of , which ran from Spokane to BC 6 .. Spokane. Spokane, Washington. Newport. Newport, Washington. Originally created in 1964 , SR 31 extended southeast to an intersection with -LRB- US 2 , formerly -RRB- in Newport .. Newport. Newport, Washington. The North Cascades Highway -LRB- SR 20 -RRB- was extended to Newport in 1973 and SR 31 from Newport to Tiger became SR 20 .. Tiger. Tiger, Washington. SR 20. Washington State Route 20. Newport. Newport, Washington. North Cascades Highway. North Cascades Highway. SR 31 had one auxiliary route , , which became SR 211 after SR 20 was extended .. SR 20. Washington State Route 20. auxiliary route. auxiliary route
not_related.