Service number (United States Navy)

United States Navy service numbers were created in 1920, one year after the close of the First World War. The creation of Navy service numbers coincided with those of the Marine Corps, as the Marines were under the authority of the Department of the Navy.

Navy officer service numbers were simple in design since the Navy officer corps in 1920 was relatively small and there was little need for a complex service number system. The first Navy service numbers, which ranged from 1 to 500, were designated for retroactive presentation to retired naval officers who had served in the First World War and prior. There was much discussion within the Navy as to which Navy officer should receive Navy service #1, with suggestions ranging from George Dewey to John Paul Jones. In the end, the Navy never proceeded with the retroactive presentation of officer service numbers and the first five hundred numbers remained un-issued.

The service numbers 501 to 999 were reserved for officers who were then serving on active duty in 1920. The first thirty service numbers (501 – 531) were issued but never recorded. It is possible that these were retroactive but the Navy did not keep records of which officers held these numbers. The first service number of file was #532 which was issued to Samuel R. Colhoun who was a Captain in the Navy Supply Corps with service in both the Spanish–American War and the Civil War. The Navy continued to issue further service numbers to other officers based on seniority within the Navy.

In 1922, the Navy extended the service number range of officers to 10,000 and by 1925 had extended the range again to 100,000. The issuance of service numbers was based simply by date of commission within the Navy; by 1929, the Navy saw the need to extend this range again to 125,000. The cap of 125,000 had just barely been reached by the outbreak of World War II in 1941.

During the Second World War, Navy officer service numbers were extended to 350,000; these numbers were simply issued by entry date into the Navy officer corps without regard to membership in the Regular Navy or United States Navy Reserve. In 1945, with the service number cap now reached, the Navy extended officer service numbers again to 600,000.

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