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 average annual 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. 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.