Washington State Route 536
[3] The highway travels east through farmland before following the Skagit River southeast into Mount Vernon.The highway turns east at Skagit Station onto Kincaid Street and crosses a BNSF rail line before ending at a diamond interchange with I-5.[7][8] The highway, first codified as the Anacortes branch of PSH 1 in 1937,[9] began at the Anacortes Ferry Terminal and traveled south to SR 525, turning east and traveling over the Swinomish Channel, leaving Fidalgo Island.[13] US 99 and PSH 1 were replaced by I-5 in segments between 1966 and 1970,[11] as SR 536 was widened, paved, and extended east to a new interchange.[15] The highway's eastern terminus at I-5 was expanded into a full diamond interchange in 1975 as part of a project to rebuild the freeway through Mount Vernon.