Analysis of information sources in references of the Wikipedia article "Washington State Route 525" in English language version.
Secondary State Highway No. 1D; beginning at a junction with Primary State Highway No. 1 in the vicinity southeast of Anacortes, thence southerly by the most feasible route by way of Deception Pass to the vicinity of Columbia Beach in the southern portion of Whidby Island; Secondary State Highway No. 1I; beginning at Everett on Primary State Highway No. 1, thence in a westerly direction by the most feasible route to Mukilteo, thence in a southeasterly direction by the most feasible route to a junction with Primary State Highway No. 1 in the vicinity south of Everett.
