- State Route 530 (SR 530) is a state highway in western Washington, United States. It serves Snohomish and Skagit counties, traveling 50.52 miles (81.30 km) from an interchange with Interstate 5 (I-5) southwest of Arlington past SR 9 in Arlington and Darrington to end at SR 20 in Rockport. Serving the communities of Arlington, Arlington Heights, Oso, Darrington and Rockport, the roadway travels parallel to a fork of the Stillaguamish River from Arlington to Darrington, the Sauk River from Darrington to Rockport and the Whitehorse Trail from Arlington to Darrington.