Between 1880 and 1920, several inventors in St. Louis, Missouri, made pioneering contributions to the development of commercial adding machines. The inventions of Frank S. Baldwin, William S. Burroughs, the brothers William W. and Hubert H. Hopkins, and their associates did much to make mechanical arithmetic commonplace in US business.
['Peggy Aldrich Kidwell']
The adding machine fraternity at St. Louis: creating a center of invention, 1880-1920