The bridge was the final link in what was then called the Pacific Highway (later known as U.S. Route 99), which ran from Canada to Mexico. The bridge crosses the Lake Union section of the Lake Washington Ship Canal and, unlike earlier bridges across the canal, the height of the Aurora Bridge eliminated the need for a drawbridge. In 1930 Seattle City Council voted to build connecting portions of the highway through the Woodland Park Zoo, a decision which generated considerable controversy at the time.