 US 2 follows the route of several wagon roads and early state highways that themselves followed the route of the Skykomish River and the Great Northern Railway, a transcontinental railroad that was completed in 1893.A wagon road from Snohomish to Skykomish was completed in the late 1880s, while another wagon road along the Wenatchee River from Leavenworth to Sunnyslope was completed by 1904.The modern-day route of US 2 between Snohomish and Monroe was completed as a county wagon road in 1904.