on, the current route of SR 599 became known as US 99T (Temporary) and later SR 99T in 1964. In 1971, the highway became SR 599. SR 181 was temporarily routed alongside the freeway on Interurban Avenue until 1971. Exit list References External links Highways of Washington State Traffic camera for SR 599 I-5 Interchange (WSDOT) 599 U.S. Route 99 Freeways in the United States Transportation in King County, Washington