St. Clair Township, now formed from the amalgamation of Moore and Sombra Townships on January 1, 2001, takes its name from the St. Clair River along its western boundary. Lake St. Clair and the St. Clair River were named after St. Claire of Assisi by French explorer René-Robert Cavalier de La Salle, who arrived on the lake on her feast day, August 12, 1679. Before 1829, St. Clair District or Township was the unorganized northern part of the Western District, which consisted of Essex and Kent counties, including the area that later became Lambton County. Those boundaries remained until 1849, when the Western District became the United Counties of Essex, Kent and Lambton. Lambton began functioning as a provisional county under Essex County in 1852 and became an independent county in 1853. South from Lake Huron, Lambton County’s riverfront townships were Sarnia, Moore and Sombra, and their boundaries stayed mostly unchanged from 1849 until 2000.