Castle Shannon is a borough in Allegheny County, Pennsylvania, United States.

[7][8] Over time, the farm would lend its name to the area, as "Shanahan" would evolve into "Shannon".

[9] In 1877, a second railroad was built from Finleyville through Castle Shannon to the West End neighborhood of Pittsburgh.

The Pittsburgh and West Virginia Railroad, still active today, came shortly afterward.

From that group, Elmer J Zeiler, a WWI Medal of Valor winner from the US and France, and a double Purple Heart recipient, was named the first Chief of Police in Castle Shannon when the police department was formed.

Castle Shannon was incorporated as a borough in 1919, formed from parts of Baldwin Township, Mt.

According to the United States Census Bureau, the borough has a total area of 1.6 square miles (4.1 km2), all land.

[10] Castle Shannon has five borders, including Baldwin Township to the north, the Pittsburgh neighborhood of Overbrook to the northeast, Whitehall to the east and southeast, Bethel Park to the south and southwest, and Mt.

A portion of Castle Shannon is zoned to Bethel Park School District.