When the current state highway numbering system was first posted in January 1964, SR 536 began at the state ferry terminal in Anacortes and headed east via Sharps Corner and Fredonia to Mount Vernon. SR 536 ended at Jct I-5 in Mount Vernon. The North Cascades Highway-SR 20 was completed in September 1972. The following year, SR 536 from Sharps Corner to Fredonia was redesignated as part of the western extension of SR 20 to Jct US 101 at Discovery Bay. Sr 536 from the ferry terminal in Anacortes to Sharps Corner became SR 20 Spur. Today, the remaining SR 536 from Jct SR 20 at Fredonia to Jct I-5 in Mount Vernon is 5.38 miles long.
Before 1964, SR 536 had been the Anacortes Branch of PSH 1.
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