Chilliwack in the context of "Fraser Valley Regional District"

Sumas Mountain, also referred to as Canadian Sumas to distinguish it from an identically named mountain just 10 km (6.2 mi) to the south in U.S. state of Washington across the border, is a mountain in eastern Fraser Lowland, in the Lower Mainland region of the Canadian province of British Columbia. It sits on the south bank of the Fraser River, west of the smaller Chilliwack Mountain across the Vedder River mouth, and serves as a geographic landmark dividing the Fraser Valley into "Upper" and "Lower" sections. Sumas Peak is an official name for the summit located on the south shore of the Fraser River in the Fraser Valley between Abbotsford and Chilliwack. Elevation 910 m (2,986 ft) above sea level, prominence 875 m (2,871 ft).

The mountain is separated from the Vedder Mountain and the North Cascades by the drained Sumas Lake, now a flatland referred to as Sumas Prairie that is part of the greater floodplain of the Fraser River basin, south of which is a same-named sister mountain—American Sumas—in Washington's Whatcom County. West of the mountain is Matsqui Prairie, another floodplain, and north of the Fraser, which lies along the mountain's north flank, are similar floodplains—Nicomen Island and Hatzic Prairie.

The Central Fraser Valley Regional District was a regional district in the province of British Columbia, Canada, located in the Lower Mainland region, south of the Fraser River and west of Chilliwack. It comprised the Township and City of Langley, the Village of Abbotsford, and the Districts of Matsqui and Sumas, plus adjoining unincorporated areas (Sumas Mountain and Vedder Mountain).

The regional district was abolished in 1995, with the Township and City of Langley being added to an enlarged Greater Vancouver Regional District and Abbotsford, Matsqui and Sumas, now incorporated together as the City of Abbotsford, added to the new Fraser Valley Regional District, which also includes the eastern half of the former Dewdney-Alouette Regional District and all of the former Regional District of Fraser-Cheam.