Sumas Prairie is a landform in British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 and the State of Washington, United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Part of the Fraser Lowland

Fraser Lowland

The Fraser Lowland is a landform and physiographic region of the Pacific Northwest, in the Canadian province of British Columbia and the U.S. state of Washington. It includes much of the Lower Mainland region of British Columbia and a portion of Whatcom County, south of the Canada–US border...

, it was created by the draining of Sumas Lake

Sumas Lake

Sumas Lake was a body of water between Sumas and Vedder mountains, midway between the present-day cities of Chilliwack and Abbotsford, British Columbia. Its name means "a big level opening" and is a reference to the site of the lake, which lay between Sumas Mountain and its American counterpart,...

 early in the 20th Century, and extends from the Vedder Canal southwestwards into northern Whatcom County, Washington

Whatcom County, Washington

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 2010, the population was 201,140. The county seat is at Bellingham, which is also the county's largest city...

. All of its Canadian portion, except its northeasternmost area around the community of Yarrow

Yarrow, British Columbia

Yarrow is a small community located 90 kilometres east of Vancouver and 12 km southwest of downtown Chilliwack, in British Columbia, Canada. It is in the Fraser Valley at the foot of Vedder Mountain. The village was first settled by Mennonites in the late 1920s, following the draining of...

, which is part of today's City of Chilliwack

Chilliwack, British Columbia

Chilliwack is a Canadian city in the Province of British Columbia. It is a predominantly agricultural community with an estimated population of 80,000 people. Chilliwack is the second largest city in the Fraser Valley Regional District after Abbotsford. The city is surrounded by mountains and...

, was formerly the District of Sumas, which was amalgamated into the City of Abbotsford

Abbotsford, British Columbia

Abbotsford is a Canadian city located in the Lower Mainland of British Columbia, adjacent to Greater Vancouver. It is the fifth largest municipality in British Columbia, home to 123,864 people . Its Census Metropolitan Area, which includes the District of Mission, is the 23rd largest in Canada,...

in 1972.