How it started
Early years
George Westinghouse founded Union Switch & Signal Inc. in 1881, consolidating the assets of the Union Electric Signal Company (founded by track circuit inventor William Robinson) and the Interlocking Switch & Signal Company (which had pioneered interlockings). In 1925, US&S acquired the Hall Signal Company, primarily to obtain the latter company's patents for searchlight signals.
Corporate management
US&S operated as an independent company until 1917, when it became a subsidiary of the Westinghouse Air Brake Company (WABCO). In 1968, American Standard purchased WABCO and reorganized US&S as a separate division.
In 1988, Ansaldo STS, a global supplier of signaling, control and automation systems, purchased US&S from American Standard. In November 1993, US&S became a publicly traded company with shares listed on Nasdaq. In December 1996, US&S merged with the other signaling investments of Ansaldo. As a result of that merger, US&S became a wholly owned subsidiary of Ansaldo STS. The company was renamed Ansaldo STS – USA in January 2009. Ansaldo was acquired by Hitachi and Ansaldo STS became Hitachi Rail STS in 2019.
Throughout its history, US&S had manufacturing facilities in the borough of Swissvale, Pennsylvania. The Swissvale plant was closed in 1985 and demolished in 1986. US&S moved manufacturing operations to a facility in Batesburg-Leesville, South Carolina. It maintained a research facility in Pittsburgh.
From Wikipedia’s article on Union Switch & Signal, shared under CC BY-SA 4.0.2