the signing of the Federal Aid Highway Act of 1956, which included funds for upgrading SSH 2A into a freeway. The highway, also known as the Renton Freeway, would follow the new SSH 2A roadway and include a new connection to Lynnwood. Construction of a new alignment for SSH 2A began in 1953; the section between Bellevue and Kirkland was completed in October 1956 after two years of construction that was slowed by difficult soil conditions. The former alignment on Lake Washington Boulevard and Market Street through Kirkland was transferred to the city government. SSH 2A and the eastern portion of SSH 1L were replaced in 1957 by the Renton branch of PSH 1, created to consolidate the bypass into a single numbered highway. In 1957, the Washington State Highway Commission approved accelerated plans to build new two-lane sections of the future freeway corridor that would be designed to accommodate later expansions to four lanes with limited access to adhere to Interstate standards. By the end of the year, the new highway had been extended north to Juanita and the southern outskirts of Woodinville. Interstate construction The American Association of State Highway Officials approved Interstate 405 as the designation for the Seattle bypass freeway in November 1958, based on a proposal submitted by the Washington State Department of Highways. On October 23, 1958, a dual ribbon-cutting ceremony marked the completion of the Renton–Kennydale and Kirkland–Woodinville sections of the initial highway. The northern extension, which terminated with a connection to Woodinville Drive, took five months to construct and included several new overpasses. The highway's completion spurred economic growth in Bellevue, which was sought due to its location near a junction with US 10; from 1955 to 1958, the city and its surrounding areas had grown from a population of 27,600 to 41,750. Expansion of the existing two-lane highway into a freeway began with a section between Factoria and Downtown Bellevue that opened in 1961. The project included a cloverleaf interchange at Northeast 8th Street in Downtown Bellevue. A nearby interchange at Northrup Road was rebuilt in 1963 to temporarily accommodate traffic from the then-new Evergreen Point Floating Bridge using a hybrid cloverleaf design. Construction of the permanent interchange was later completed in November 1966 at a cost of $5.5 million. In 1964, the system of primary and secondary state highways was removed in favor of new state routes, and the incomplete