SR 548 continues north through the beach community of Birch Bay, overlooking a section of Boundary Bay. The highway then crosses over California Creek near the Loomis Trail Golf Club and Dakota Creek at the southern city limit of Blaine. The highway crosses over the BNSF Bellingham Subdivision and turns northwest onto Peace Portal Drive, traveling parallel to I-5 and the railroad through Blaine.[4][10] The highway and the railroad move onto the shore of Drayton Harbor, part of Semiahmoo Bay, and travel north through downtown Blaine.[11] SR 548 reaches its terminus at a dogbone interchange with I-5, signed as exit 276, near the city's marina, approximately 1⁄2 mile (0.8 km) from the Peace Arch crossing of the Canadian border.[8] The interchange also includes ramps to D Street, which continues east to SR 543,[11] and 2nd Street, which connects to a parking lot for Peace Arch State Park.[9][12]
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 annual average 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.[13]
SR 548 was created in 1991 from the county- and city-maintained Peace Portal Drive, Blaine Road, and Grandview Road between Ferndale and Blaine.[22][23] In 2010, WSDOT improved the I-5 interchange in Blaine at a cost of $13.2 million by converting it to a dogbone interchange using two new roundabouts.[24] A roundabout was constructed at the Cherry Point Refinery in 2018.[7]
^Washington State Legislature (March 12, 1913). "Chapter 65: Classifying Public Highways". Session Laws of the State of Washington (1913 ed.). Olympia, Washington: Washington State Legislature. p. 221. Retrieved February 1, 2013. A highway starting at the international boundary line at Blaine, Washington; thence southerly by the most feasible route through the cities of Bellingham, Mount Vernon, Everett, Seattle, Renton, along the easterly side of the White River Valley through Kent, Auburn, Tacoma, Olympia, Tenino, Centralia, Chehalis, to the southern boundary line at the city of Vancouver, Washington, to be known as The Pacific Highway.
^Washington State Legislature (March 19, 1923). "Chapter 185: Primary and Secondary State Highways". Session Laws of the State of Washington (1923 ed.). Olympia, Washington: Washington State Legislature. pp. 627–628. Retrieved February 1, 2013. SECTION 1. A primary state highway, to be known as State Road No. 1 or the Pacific Highway, is established as follows: Beginning at the international boundary line at Blaine in the County of Whatcom; thence by the most feasible route in a southerly direction to the interstate bridge over the Columbia River between Vancouver and Portland.
^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. Retrieved February 1, 2013. Beginning at the international boundary line in the vicinity of Blaine in Whatcom county, thence in a southerly direction by the most feasible route to the Washington-Oregon boundary line on the interstate bridge over the Columbia river.
^"SR-548 Route Development Plan". Washington State Department of Transportation. February 1997. p. 2-1. Retrieved October 7, 2021 – via WSDOT Library Digital Collections.