 The old route to the east was signed by the state as Secondary State Highway 2A (SSH 2A) from 1937 to 1943 and SSH 2J from 1957 to 1964, when it was renumbered as SR 527.Since its opening, suburban development in Mill Creek and northern Bothell has contributed to traffic congestion on stretches of SR 527.During the 1990s and early 2000s, the state government funded several projects that widened the highway to its present four-lane configuration with sidewalks, bus pullouts, and bicycle lanes.