SR 542 begins as Sunset Drive and the Mount Baker Highway at a partial cloverleaf interchange with I-5 to the northeast of downtown Bellingham.[3] The highway travels northeast through suburban neighborhoods along Squalicum Creek and passes Squalicum High School as it leaves the city of Bellingham. SR 542 continues northeast through rural Whatcom County, crossing the Nooksack River and intersecting SR 9 at a roundabout. The concurrent SR 9 and SR 542 travel southeast through the community of Deming along a BNSF rail line and passes Mount Baker Senior High School.[4] SR 542 leaves SR 9 east of Deming and turns north along the North Fork of the Nooksack River and the eastern slope of Sumas Mountain to Kendall, where it serves as the southern terminus of SR 547. The Mount Baker Highway turns east and continues along the Nooksack River North Fork into the Mount Baker-Snoqualmie National Forest at Glacier in the foothills of Mount Baker.[5] SR 542 turns south and serves the Mt. Baker Ski Area on the northeast side of the mountain before splitting into a one-way pair around Picture Lake.[6][7] The Mount Baker Highway continues through Austin Pass and ends at Artist Point, located at 5,210 feet (1,588.01 m) above sea level on Kulshan Ridge.[1][8]
Table Mountain reflected in roadside pond near Austin Pass
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 SR 542 was the I-5 interchange in Bellingham, serving 38,000 vehicles, while the least busy section of SR 542 was the one-way pair around Picture Lake in Mount Baker-Snoqualmie National Forest, serving 230 vehicles.[9] The Mount Baker Highway is designated as a National Forest Scenic Byway and serves as the eastern section of the Ski to Sea Race between Mount Baker and Maple Falls, a 90-mile (140 km) Memorial Day race with seven legs hosting seven events.[10][11][12] The eastern terminus of SR 542, at Artist Point on Kulshan Ridge, is only open in the summer between July and October due to extreme weather conditions.[13][14][15]
A rock wall collapse on October 12, 2020, closed access to the Artist Point section of SR 542 for ten months while repairs were made. The rock wall was rebuilt by WSDOT and the section was reopened in August 2021.[34]
^2011 Washington State Rail System(PDF) (Map). Washington State Department of Transportation. January 2012. Archived from the original(PDF) on June 12, 2013. Retrieved February 21, 2013.
^"SR 542: Junction SR 542 CO MTBAKR"(PDF). Washington State Department of Transportation. April 28, 2006. Archived(PDF) from the original on March 4, 2016. Retrieved February 21, 2013.
^Staff (2011). "2011 Annual Traffic Report"(PDF). Washington State Department of Transportation. pp. 206–207. Archived(PDF) from the original on June 13, 2013. Retrieved February 21, 2013.
^Washington: Mt. Baker District(JPG) (Map). 1:250,000. United States Geological Survey. May 1915. Archived from the original on March 13, 2011. Retrieved February 23, 2013.
^Washington State Legislature (February 18, 1925). "Chapter 26: An Act relating to and establishing, classifying, naming and fixing the routes of certain state highways". Session Laws of the State of Washington (1925 ed.). Olympia, Washington: Washington State Legislature. p. 59. Retrieved February 23, 2013. Section 1. A primary state highway, to be known as State Road No. 1 or the Pacific Highway, is established as follows: From a junction in the city of Bellingham; thence by the most feasible route in an easterly direction to Austin Pass in Whatcom County.
^Washington State Legislature (March 17, 1937). "Chapter 190: Establishment of Primary State Highways". Session Laws of the State of Washington (1937 ed.). Olympia, Washington: Washington State Legislature. p. 933. Archived from the original on October 1, 2013. Retrieved February 23, 2013. SECTION 1. 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: Also beginning at Bellingham on Primary State Highway No. 1, as herein described, thence in an easterly direction by the most feasible route to a point in the vicinity of Austin Pass in Whatcom county.
^Victoria, 1966(JPG) (Map). 1:250,000. United States Geological Survey. 1966. Archived from the original on October 16, 2012. Retrieved February 23, 2013.
