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Illinois Serial Number 4000000-5500000 Date & Production Guide
Guild Home > Archive > Illinois Serial Number 4000000-5500000 Date & Production Guide

Serial Number & Production Dating Lookup

Enter the 5 to 8 digit serial number stamped directly on the movement plate (not the watch case):

ILLINOIS SERIAL REGISTRY 1890 – 1930 Assigned Serial Range 4,000,000 – 5,500,000 Estimated Era circa 1890 – 1930 Serial Number Dating Archival Production Lot 4,000,000 1890 Early Production Lot 4,375,000 1900 Standard Factory Run 4,750,000 1910 Mid-Era Production 5,125,000 1920 Late Milestone Lot 5,500,000 1930 End of Block Registry Official Archival Chronology • American Watch Guild Registry VERIFIED ARCHIVE
Official Serial Archive • Illinois Historical Registry Ledger

Technical Specifications & Factory Archival Records

Range4000000-5500000
Vibrations Per Hour18,000 BPH (2.5 Hz)
Balance Lift Angle50°
Power Reserve39 hours
Escapement TypeSafety pinion lever
Balance Wheel ConstructionBimetallic compensation balance with gold screws
Hairspring SpecificationBreguet overcoil hairspring
Shock Protection SystemNone (Solid jewel settings)

Horological Architecture & Collector Notes

The American pocket watch was engineered to meet rigorous American horological standards during the turn of the 20th century. Utilizing high-grade alloy components, a precision Safety pinion lever, and 15 jewels with fine ruby endstones, this movement provided exceptional isochronism and positional stability.

Among vintage restorers and conversion specialists, this series is admired for its accessible gear train geometry and solid metallurgy, making surviving specimens excellent candidates for preservation and custom recasing. For examples of restored and converted specimens, see AntiqueWrist Atelier.

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