I-5 northbound approaching its interchange with SR 536 in Mount Vernon.
SR 536 begins as the Memorial Highway at an intersection with SR 20 located south of Skagit Regional Airport and east of Fredonia.[3] The highway travels east through farmland before following the Skagit River southeast into Mount Vernon. SR 536 crosses the Skagit River on a swing bridge into Downtown Mount Vernon, turning east onto Division Street and south onto 3rd Street. The highway turns east at Skagit Station onto Kincaid Street and crosses a BNSF rail line before ending at a diamond interchange with I-5.[4][5]
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 between 4,600 and 23,000 vehicles per day used the highway, mostly in Downtown Mount Vernon.[6]
The bridge over the Skagit River was rebuilt by the state government in 1954, at a cost of $1.03 million.[13] US 99 and PSH 1 were replaced by I-5 in segments between 1966 and 1970,[11] as SR 536 was widened, paved, and extended east to a new interchange.[2][14] SR 20 was extended west to Whidbey Island and the Olympic Peninsula over SR 536 and SR 525 in 1973, shortening SR 536 to its current route and creating SR 20 Spur in Anacortes.[15] The highway's eastern terminus at I-5 was expanded into a full diamond interchange in 1975 as part of a project to rebuild the freeway through Mount Vernon.[16][17]
^Staff (2011). "2011 Annual Traffic Report"(PDF). Washington State Department of Transportation. p. 205. Archived from the original(PDF) on June 13, 2013. Retrieved February 1, 2013.
^Staff (1960). "Annual Traffic Report, 1960"(PDF). Washington State Highway Commission, Department of Highways. p. 54. Archived from the original(PDF) on March 13, 2011. Retrieved February 1, 2013.
^Washington State Legislature (March 17, 1937). "Chapter 185: Establishment of Primary State Highways". Session Laws of the State of Washington (1937 ed.). Olympia, Washington: Washington State Legislature. p. 933. Retrieved February 1, 2013. A primary state highway to be known as Primary State Highway No. 1, or the Pacific Highway, is hereby established according to description as follows: Beginning at Mt. Vernon on Primary State Highway No. 1, as herein described, thence in a westerly direction by the most feasible route to Anacortes.
^Patty, Stanton (November 4, 1954). "New Bridge Ends Detour In Mount Vernon". The Seattle Times. p. 41.
^Staff (1970). "Annual Traffic Report, 1970"(PDF). Washington State Highway Commission, Department of Highways. pp. 204–205. Archived from the original(PDF) on October 17, 2013. Retrieved February 1, 2013.
