In 2011, WSDOT calculated that the busiest section of SR 501 overall was west of I-5 at C Street, serving 13,000 vehicles, while the least busiest section of SR 501 overall was south of Shillapoo Wildlife Recreation Area, serving 650 vehicles. Between I-5 and the Port of Vancouver, SR 501 is designated as part of WSDOT's Highway of Statewide Significance, which include interstate highways and other principal arterials that are needed to connect major communities in the state of Washington.
In 2011, WSDOT noted that the busiest section of SR 501 was west of I-5 at C Street with 13,000 vehicles; conversely, the least busy part was south of Shillapoo Wildlife Recreation Area with 650 vehicles. Between I-5 and the Port of Vancouver, SR 501 is classified as a Highways of Statewide Significance by WSDOT, which includes interstate highways and other major routes essential for connecting key areas in Washington.