Sumas is a small town in Whatcom County, Washington, United States. The population was 1,307 at the 2010 census. Sumas is located adjacent to the Canadian border and borders the city of Abbotsford, British Columbia. The Sumas-Huntingdon port of entry at the north end of State Route 9 operates 24 hours a day. Sumas shares Nooksack Valley School District with the towns of Nooksack and Everson.
Sumas was officially incorporated on June 18, 1891. Established first as a trading post in the late 1850s, it grew in size and importance as the junction of three railroads and a border crossing into Canada. The name, Sumas, comes from a local native tribal word meaning "land without trees." The broad valley in which Sumas is located is called Sumas Prairie. Before settlers built canals and dams, the lower valley was marshland and covered in shallow flood-filled lakes. The abundance of large trees in the surrounding hills attracted loggers and helped the city grow. In 1897, gold was discovered in the mountains nearby and Sumas quickly grew to more than 2,000 residents as gold miners and mining suppliers moved in. After the gold rush subsided and trees were cleared, the town began to shrink and businesses shifted to support the growing farming industry surrounding the town. Dairy farms sprouted in the valley and still play an important role in the area's economy. The farmers, many of Dutch origin, and other area towns further tamed the flood prone valley with a series of dikes and channels. This opened the valley to an abundance of dairy and crop farming. Today, Sumas hosts several forest products businesses as well as businesses supporting farms in the surrounding area.
In 1999, a proposal was put forth to build a cogeneration electric generator in Sumas. This project was known as Sumas 2 until it was canceled in 2006.