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 determined that the most trafficked part of SR 501 was west of I-5 at C Street, handling 13,000 vehicles; conversely, the least trafficked section of SR 501 was south of Shillapoo Wildlife Recreation Area, managing 650 vehicles. Between I-5 and the Port of Vancouver, SR 501 is classified as part of WSDOT's Highways of Statewide Significance, which encompass interstate highways and other major thoroughfares necessary for connecting key communities in Washington state.