 US 10 was re-routed in 1939 and replaced by US 10 Alternate, which was routed across Stevens Pass in the 1940s and itself replaced by US 2 in 1946.The primary state highways were replaced by the current state route system during the 1964 state highway renumbering, and US 2 replaced its three concurrent routes.US 2 underwent conversions to limited-access highways during the next several decades, including the completion of the Hewitt Avenue Trestle and a bypass of Snohomish.