The Alaskan Way Viaduct was built in three phases in 1949 through 1953 and opened on April 4, 1953. It features a double-decked elevated section of State Route 99 that runs along the Elliott Bay waterfront in the industrial district and downtown of Seattle. It is the smaller of the two major north–south traffic corridors through Seattle (the other being Interstate 5), carrying up to 110,000 vehicles per day. The viaduct runs above the surface street, Alaskan Way, from S. Nevada Street in the south to the entrance of Belltown's Battery Street Tunnel in the north, following previously existing railroad lines.
The viaduct was damaged in the 2001 Nisqually earthquake. The initial phase of demolition and removal of the southern viaduct began on October 21, 2011. Boring of the Alaskan Way Viaduct replacement tunnel began in 2013; the viaduct will be rebuilt to modern seismic standards for the industrial area south of downtown.