State Route 526 (SR 526), also known as the Boeing Freeway, is a state highway in Snohomish County, Washington, United States. The east–west highway travels 4.52 miles (7.27 km) and connects SR 525 in Mukilteo to Interstate 5 (I-5) in southern Everett. The highway serves the Boeing Everett Factory and Paine Field; it also serves as a main route to the city of Mukilteo and the state-run ferry to Whidbey Island.