 SR 27 was first codified as part of the Second Division of the Eastern Route of the Inland Empire Highway between Pullman and Oakesdale in 1913 and later became a paved branch of PSH 3 during the creation of the primary and secondary state highways in 1937 . The branch route traveled 68 @.@ 71 miles ( 110 @.@ 58 km ) north from US 195 at the Idaho state border through Pullman and Oakesdale to PSH 3 and US 195 south of Rosalia . SSH 3H was also established in 1937 , traveling 38 @.@ 69 miles ( 62 @.@ 27 km ) north from the PSH 3 branch in Oakesdale through the Palouse to PSH 2 and US 10 in Spokane Valley . The two highways were combined to form SR 27 during the 1964 highway renumbering , part of a new state highway system still in place today . A western bypass of Pullman for US 195 was originally planned in the late 1960s and was opened in 1974 as part of a proposed ring road around the city . US 195 was routed onto the completed segment and SR 27 was extended south over its former route to intersect the new highway in 1975 , while the rest of the bypass would become the un @-@ built SR 276 . The highway was extended north within Spokane Valley from its interchange with I @-@ 90 to Trent Avenue , signed as SR 290 , in 1991 . The highway between Pullman and Tekoa was designated as part of the Palouse Scenic Byway on December 19 , 2002 , as part of the Washington State Scenic and Recreational Highways program . The scenic byway was extended north in 2011 to SR 278 in Rockford . 
