At the start of the twentieth century, it had extensive foundries and machine shops of the Westinghouse Air Brake Company.

Wilmerding is adjacent to the borough of Turtle Creek, which takes its name from a small stream that flows past both places.

Westinghouse then sold the land to the East Pittsburgh Improvement Company, incorporated in December 1888, to develop the site, and it began the sale of lots in June 1889.

[5] Wilmerding's most notable historic structure is the Westinghouse Air Brake Company General Office Building (1889–1890, rebuilt 1896), designed by Frederick J. Osterling and now listed on the National Register of Historic Places.

[8] According to the United States Census Bureau, the borough has a total area of 0.4 square miles (1.0 km2), all land.

Wilmerding neighbors five borders, including Monroeville to the northeast, Wall to the east, East McKeesport to the south, North Versailles Township to the southwest, and Turtle Creek (via Greensburg Pike/Lincoln Highway Bridge) to the northwest.