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. 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 BNSFrail line and passes Mount Baker Senior High School. 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. 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. The Mount Baker Highway continues through Austin Pass and ends at Artist Point, located at above sea level on Kulshan Ridge. Every year, the Washington State Department of Transportation conducts a series of surveys on its highways in the state to measure traffic volume. This is expressed in terms of average annual daily traffic, 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. 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 Memorial Day race with seven legs hosting seven events. The eastern terminus of SR 542, at Artist Point on Kulshan Ridge, is closed annually by WSDOT between October and July due to extreme weather conditions.
History
The Mount Baker Highway was constructed by Whatcom County in 1893 as a wagon road traveling northeast from Bellingham along the Nooksack River through Deming and Kendall to Maple Falls. The wagon road was extended from Maple Falls through Glacier to the Mt. Baker Ski Area at Heather Meadows began 1921 and ended in 1926. The Mount Baker Highway was added to the state highway system in 1925 as the Austin Pass branch of State Road 1 and was extended to its current terminus at Artist Point in 1931. The highway was closed seasonally between Glacier and Artist Point until the filming of The Call of the Wild in 1934 and 1935 prompted interest in the Mount Baker area. The Department of Highways began clearing the highway of snow during the winter of 1934 for the film and continued annually between Glacier and Heather Meadows; however, the highway was not cleared during World War II due to gasoline shortages. The highway was designated as the Austin Pass branch of PSH 1 during the creation of the primary and secondary state highways in 1937 and renumbered to SR 542 in 1964. The entire route, between Bellingham and Austin Pass, was designated as part of the Washington State Scenic and Recreational Highways program in 1987 and a National Forest Scenic Byway on November 1, 1988.
