| Accurate Time Stamp Company | West Virginia. Some Stahlberg patents are assigned to this company. | | | Yes |
| A. L. Swift | Chicago. Name seen on dials of the cast iron stove clock. | | | Yes |
| American Cyanamid Company | Manufacturer of Beetle® and Melmac® molded plastics for clock cases, telephone housings, etc. Address given as PLASTICS DEPARTMENT, 34 Rockefeller Plaza, New York 20, N.Y. in a 1950 advertisement. | | | Yes |
| Ansonia | The Ansonia Clock Co. has its roots in Bristol, CT. Theodore Terry, nephew of Eli Terry, and F. C. Andrews formed the firm Terry & Andrews in 1841 to manufacture inexpensive brass movement clocks. The . . . | | | Yes |
| Arnex | Maker of reproduction watches with mechanical movements in the 1970s. | | | Yes |
| Bulova | Bulova Watch Company. Imported Swiss watch movements and cased them in the USA. | | | Yes |
| Catalin Corporation of America | Manufacturer of Catalin plastic used in clock cases. Address: One Park Avenue, New York 16, N.Y. in 1947 advertisement. | | | Yes |
| Chelsea | Chelsea Clock Company. Founded in 1884 as Boston Clock Company, became Chelsea in 1897. Well known for ship's bell clocks. Still making clocks in the USA. | | | Yes |
| Columbia Time Products | A name Westclox used ca. the 1950s - 1960s on some private label or lower priced clocks. | Westclox | | No |
| Deemer Mfg. co. | Chicago, IL. Name on the back of the case iron stove clocks. | | | Yes |
| Dura Company | Toledo, Ohio, maker of cast cases such as the Westclox Dura Case models | | | Yes |
| Eastern Time Limited | Hong Kong, maker of clocks and movements for Westclox. Founded ca. 1964. | Westclox | | No |
| E. Howard Watch Co. | Base company for E. Howard and Howard watches | | | Yes |
| Eico | Maker of electronic kits including hi-fi, stereo and test equipment. Electronic Instrument Company, Inc. 33 - 00 Northern Blvd., Long Island City 1, N.Y. Eico pioneered build-it-yourself kits for test . . . | | | Yes |
| Elgin | Made watches in the USA from 1864 to 1968. | | | Yes |
| General Electric | Part owner of Warren Telechron Company. Marketed clocks with the General Electric name. | Telechron | | No |
| General Electric Telechron | Name used in the mid-1950s on clocks. | Telechron | | No |
| General Time | This is the base company for General Time Instruments Corp. and General Time Corp. | | General Time Corporation; General Time Instruments Corporation | Yes |
| General Time Corporation | Holding company for Westclox and Seth Thomas starting in 1949. | General Time; Seth Thomas; Westclox | | No |
| General Time Instruments Corporation | Holding company for Westclox and Seth Thomas 1936 - 1949. | General Time; Seth Thomas; Westclox | | No |
| Gilbert | William L. Gilbert was born in 1806 in Northfield, CT (a village of Litchfield) and became interested in the booming clockmaking business at Bristol in 1828. In that year he and his brother–in–law . . . | | | Yes |
| Golden Novelty Mfg. Co. | Made cast front cases that often housed Western Clock Clock Manufacturing Company or Western Clock Company movements. Chicago, Illinois. | | | Yes |
| Gruen | Became known as Gruen Watch Company in 1922. | | | Yes |
| Hamilton | Hamilton Watch Company. Lancaster, Pennsylvania. Produced its first watch in 1893. | | | Yes |
| Hammond | Hammond Clock Company was founded in 1928 to produce electric clocks with a manual-starting synchronous motor. The company became known as the Hammond Instrument Company in 1937. They made clocks unti . . . | | | Yes |
| Haydon | Forestville, Conn and other locations. Makers of electric synchronous motors. | | | Yes |
| HECO | Henry Coehler Company, New York. Importer of 400 day and cuckoo clocks, dealer for Junghans clocks in the 1950s | | | Yes |
| Hytron Corporation | Manufacturer of vacuum tubes. Bought out by CBS in 1951. Advertisements state that Hytron developed the GT tube starting in 1938, and the first miniature (baseless) tube also in 1938. Company location . . . | | | Yes |
| Illinois Watch Company | Springfield, Illinois. | | | Yes |
| Imperial Co. | Chicago. Maker of cast front clock cases. | | | Yes |
| Ingersoll | The Ingersoll Watch Company started as mail order business (R H Ingersoll & Bro) started in New York City in 1882 by 21-year-old Robert Ingersoll and his brother Charles Ingersoll. | | | Yes |
| Ingraham | Elias Ingraham (1805–1885) was born in Marlborough, CT, and became a famous clock case maker and designer. In 1828 he came to Bristol, CT to design and make clock cases for George Mitchell, a succes . . . | | | Yes |
| Junghans | Maker of clocks and watches, still in existence, founded in Germany in 1861. | | | Yes |
| Kenmore Kodel | Kenmore clocks by The Kodel Electric & Manufacturing Co., 517 East Pearl St., Cincinnati, Ohio. | | | Yes |
| Kern and Sohn | German maker of 400 day clocks in the 1950s. | | | Yes |
| Kundo | Base company for Kieninger & Obergfell. Maker of 400 day clocks. | | | Yes |
| Lux | The Lux Clock Manufacturing Company was founded in 1914 by Paul Lux. | | | Yes |
| Mido | A watch company founded in Switzerland in 1918. Well known for their Multifort line of wrist watch waches which are self-winding, waterproof and shock resistant. Today Mido is part of the Swatch Group . . . | | | Yes |
| Minneapolis Honeywell | Minneapolis-Honeywell was created by the merger of Honeywell Heating Specialty Company and Minneapolis Heat Regulator Company in 1927. (Source Wikipedia) | | | Yes |
| Montgomery Ward | Mail order and department store retailer who marketed some clocks with their name on it. | | | Yes |
