1885 - founded as the United Clock Company, in Peru, Illinois, to manufacture clocks based on a technological innovation by Stahlberg; after being granted the 1885 patent, United Clock Company went bankrupt. 1887 - reorganized as the Western Clock Company, but also went bankrupt. 1888 - the Western Clock Manufacturing Company. 1908 - granted patent for the Big Ben alarm clock movement. 1909 - first brought to market. 1912 - company's name shortened to Western Clock Company. 1910-1917 - Westclox trademark first appeared on the backs of Big Ben alarm clocks. 1911 - Westclox name appeared on Big Ben dials. Trademark officially registered by the company on January 18, 1916. 1919 - Western Clock Co., Ltd., incorporated. 1931 - company merged with Seth Thomas Clock Company, with both companies becoming divisions of General Time Corporation. 1936 - Westclox unit became known as Westclox Division of General Time Corporation.

Westclox had a highly successful factory in Scotland situated in the Vale of Leven Industrial Estate, in Dumbarton, founded in 1948.