Upper St. Clair

The first European settler in present-day Upper St. Clair was John Fife, who settled near what is now the intersection of Washington and McLaughlin Run roads in 1762.

St. Clair was one of the original townships of Allegheny County, Pennsylvania at the county's creation in 1788. In 1836, the St. Clair Township was divided into two separate townships, Upper St. Clair and Lower St. Clair. The residents of Upper St. Clair formed their township to ensure better government service that could be obtained by separating from the more densely populated northern part of the township. Upper St. Clair Township was further subdivided throughout the 19th and 20th centuries as several parts of the original township separated to form new townships and boroughs. In 1973, Upper St. Clair Township adopted a home rule charter that took effect on January 5, 1976, and is no longer governed by the Pennsylvania Township Code.

The Whiskey Rebellion of 1794 had its roots in Upper St. Clair.

Formed as a volunteer militia company in 1844 by residents of the township, the "St. Clair Guards" later became Company H of the 62nd Pennsylvania Infantry.

The community was home to several mines beginning in the late 19th century. Freehold Real Estate Co. built the first major residential development in March 1913 along Washington Road, which at the time was conveniently close to streetcar service. During the 1930s, Upper St. Clair was recorded as a community within the city which had a school district providing regular nursing services.