St. Clair Township, Allegheny County, Pennsylvania

St. Clair Township, Allegheny County, Pennsylvania, was one of the original townships created with the incorporation of Allegheny County in 1788. The township was named after Arthur St. Clair, a Revolutionary War general and president of the Continental Congress in 1787.

The township included most of Allegheny County south of the Monongahela River. The township was subsequently divided between the northern part, Lower St. Clair Township, and the southern part, Upper St. Clair Township. The "upper" and "lower" referred to the elevation, as Lower St. Clair bordered on the river, the lowest elevation, and Upper St. Clair extended into the South Hills of Pittsburgh.

The original Lower St. Clair Township consisted of the present-day neighborhoods of the City of Pittsburgh south of the Monongahela River, and all or parts of Green Tree, Carnegie, Baldwin, and other boroughs and townships in the South Hills. The township was subdivided several times, and today exists only as the neighborhood of St. Clair in the City of Pittsburgh.

Upper St. Clair Township, subdivided many times, still exists in the South Hills of Pittsburgh.