| Name | Summary | Parent Co. | Child Co. | Is Base Co. |
|---|---|---|---|---|
| Western Clock Company 1887 | Started in 1887. | Westclox | No | |
| Western Clock Company 1912 to 1936 | Starting in 1912 | Westclox | No | |
| Western Clock Company Ltd. Canada | Western Clock Company, Ltd., Peterborough, Canada | Westclox | No | |
| Western Clock Manufacturing Company | Starting in 1888 | Westclox | No |
