Lynden is a city in Whatcom County, Washington, United States. It is located 15 miles north of Bellingham, the county seat and principal city of the Bellingham Metropolitan Area. It is the second largest city in Whatcom County. The city is approximately 5 miles (8.0 km) south of the Canada–US Border.

Whatcom County is a county located in the northwestern corner of the U.S. state of Washington, bordered by the Lower Mainland of British Columbia to the north, Okanogan County to the east, Skagit County to the south, San Juan County across Rosario Strait to the southwest, and the Strait of Georgia to the west. Its county seat and largest population center is the coastal city of Bellingham, comprising the Bellingham, WA Metropolitan Statistical Area, and as of the 2020 census, the county's population was 226,847.