An Elgin watch has two serial numbers. The movement serial number is located in the watch's gear region, and the case serial number is located on the back of the case.
The movement serial number and the case serial number often do not match on early Elgin watchers. Customers often bought the case separately from the watch itself. Watch cases tended to wear out more quickly than the watch movement, so the case is often newer than the movement it contains.
The Elgin National Watch Company manufactured watches in Elgin, Illinois, from 1864 until 1968. During World War II, Elgin manufactured artillery shell fuses, various aircraft instruments and sapphire bearings that were used for aiming cannons.