sentences:  SR 548 is maintained by the Washington State Department of Transportation (WSDOT), which conducts an annual survey of average traffic volume on state highways that is measured in terms of average annual daily traffic.Traffic volumes on SR 548 range from a minimum of 2,100 vehicles near the Cherry Point Refinery to a maximum of 12,000 vehicles near its Ferndale terminus.SR 548 between Birch Bay and Blaine follows the route of a wagon road built in the 1900s parallel to a Great Northern rail line.