Whatcom County // is a county located in the U.S. state of Washington. Its name ultimately derives from the Lummi word Xwotʼqom, meaning "noisy water." As of the 2011 census, the population was 203,663. The county seat is at Bellingham, which is also the county's largest city. Whatcom County's northern border is the international boundary with the Canadian province of British Columbia; adjoining the county on the north are four of metropolitan Vancouver's suburbs, Delta, White Rock, Surrey, Langley, and, in the central Fraser Valley, Abbotsford, with several shopping malls and other services in Bellingham and elsewhere in the county geared to cross-border shopping and recreation. The five crossing points are two at Blaine (one at the Peace Arch, located on the Interstate 5 crossing, and the other a commercial and passenger crossing on the Pacific Highway at State Route 543, both to Surrey, British Columbia), as well as at Lynden (SR 539, to Aldergrove), Sumas (SR 9, to Abbotsford), and Point Roberts (Tyee Drive, to Tsawwassen). Whatcom County is contiguous with Bellingham Metropolitan Statistical Area.
Whatcom County was created out of Island County by the Washington Territorial Legislature on March 9, 1854, and originally included present day San Juan and Skagit Counties.