Every year, the Washington State Department of Transportation (WSDOT) conducts a series of surveys on its highways in the state to measure traffic volume. This is expressed in terms of annual average daily traffic (AADT), which is a measure of traffic volume for any average day of the year. In 2011, WSDOT calculated that the busiest section of the highway was at 10th Street in Downtown Long Beach, serving 7,900 vehicles, while the least busiest section was the entrance to Leadbetter Point State Park, serving 270 vehicles.[5]
^Staff (2011). "2011 Annual Traffic Report"(PDF). Washington State Department of Transportation. pp. 132–133. Retrieved February 11, 2013.
^Washington State Legislature (March 18, 1937). "Chapter 207: Classification of Public Highways". Session Laws of the State of Washington (1937 ed.). Olympia, Washington: Washington State Legislature. p. 1008. Retrieved February 11, 2013.
^Copalis Beach, 1957(JPG) (Map). 1:250,000. United States Geological Survey. 1957. Retrieved February 11, 2013.
^Staff (1970). "Annual Traffic Report, 1970"(PDF). Washington State Highway Commission, Department of Highways. p. 122. Retrieved February 11, 2013.
^Copalis Beach, 1968(JPG) (Map). 1:250,000. United States Geological Survey. 1968. Retrieved February 11, 2013.
^Washington State Legislature (May 21, 1991). "Chapter 342: Engrossed Senate Bill 5801". Session Laws of the State of Washington (1991 ed.). Olympia, Washington: Washington State Legislature. Retrieved February 11, 2013.