The Westinghouse Electric & Manufacturing Company
Organized in 1886 as the Westinghouse Electric Company with a force of 200 men, the name of the company later became the Westinghouse Electric & Manufacturing Company. By 1904, the number of workers grew to 9,000 at the main plant with 3,000 additional employees in branch factories. It became the largest of the Westinghouse companies and was thought to be the largest and most modern workshop in the world at the time the American Mutoscope & Biograph Company filmed its operations. The Engineering Department alone employed 350 mechanical and electrical experts.
The company began building an extensive plant in 1895 in East Pittsburgh on 40 acres of land. The total floor space in the entire plant was over two million square feet.
The shop contained a long aisle in the main building "filled with large machines in various stages of construction. 
This aisle [was] seventy feet in width and 1,184 feet in length, and [was] traversed from end to end by traveling cranes of capacities ranging from thirty to fifty tons each." (Works of the Westinghouse Electric & Manufacturing Company, 1904). The largest aisle, measuring 70 feet across and one-third of a mile in length, was located in the East Machine Shop.
The main function of the Electric & Manufacturing Company was to develop and produce "apparatus for the generation, transmission and application of alternating current electricity." (The Westinghouse Companies in the Railway & Industrial Fields, 1905) The company also produced electric railway motors, producing approximately 75,000 by 1905.
The Electric & Manufacturing Company played an integral role in several notable projects, namely the conversion of Niagara Falls to electric power, the installations of the Interborough Rapid Transit Company in New York and the South Side Elevated Railroad in Chicago, and the powering of the Louisiana Purchase Exposition in St. Louis. More details on these projects is available under the heading "Projects worked on by the Westinghouse Electric & Manufacturing Company during this period."
In addition to the plant at East Pittsburgh, the Westinghouse Company had branch works at this time at Newark, NJ, and Cleveland, Ohio, as well as maintaining control over the product of the following companies: Sawyer Man Electric Co., NY; The Bryant Electric Co. and The Perkins Electric Switch Manufacturing Co., Bridgeport, Conn.; and R.D. Nuttall Co., Pittsburgh. The Electric and Manufacturing Company also had plants abroad in Manchester, England; Havre, France; and Hamilton, Canada.
(Sources for photos and information: The Westinghouse Companies in the Railway & Industrial Fields, 1905; Works of the Westinghouse Electric & Manufacturing Company, 1904)