US Army Serial Numbers

sn-examplesAmericans have been in numerous wars over the decades but it was not until February 12, 1918, that there was the introduction of US Army serial numbers (SNs). Before that date the main method of identification of soldiers was by the ‘roster rolls’ or ‘muster rolls’, the listing of soldiers during a specific time period.

The first service numbers to be issued in February 1918 were only to Army enlisted personnel. Other military branches (Navy, Marines) were still small enough not needing serial numbers. The first Army personnel issued the first number was Master Sergeant Arthur Crean. Imagine that was your ancestor and you have just learned that bit of information. After WW I in 1920, the Army introduced the first “service number prefix” which was intended to be a letter placed in front of the service number to provide additional information about the veteran. Also in 1920 was when Army officers received serial numbers, with the letter “O”, the first being issued to General John J. Pershing.

By 1942 those prefix letters were discontinued, just numbers used. New sets of numbers were used, mostly for those drafted during WW II. Other changes would come about over the next few years but by July 1, 1969, service numbers were declared discontinued. Instead, military personnel were identified by their social security number.

See below the first couple of numbers / letters and what they referred to identification of a soldier. These numbers were also placed on the ‘dog tags’ – metal tags worn by all soldiers. Another good source for additional information is this link on Army serial numbers.


Look at the First Number or Letter

Some prefixes were used in World War I. However, the following system began shortly before World War II.

The first character gives us a lot of information.

  • 1 = Enlisted in the Army (in other words, volunteered rather than drafted)
  • 2 = Federally recognized National Guard
  • 3 = Drafted
  • 4 = Drafted
  • O (that’s the letter O, not a zero) = Male commissioned officers
  • W = Male Warrant officers
  • T = Flight officers (Army Air Force)
  • L = Commissioned officers of the Women’s Army Corps (WAC)
  • V = WAC Warrant officers
  • A = WAC enlisted women
  • R = Hospital dietitians
  • M = Physical therapy aides

Look at the Second Number

When you have an 8-digit serial number, the second number shows the Service Command. This narrows down where the person enlisted or was drafted. If you have a serial number for a member of the WAC, look at the number after the letter prefix.

      *1 = Connecticut Maine, Massachusetts, New Hampshire, Rhode Island, Vermont

  • 2 = Delaware, New Jersey, New York
  • 3 = Maryland, Pennsylvania, Virginia
  • 4 = Alabama, Florida, Georgia Mississippi, North Carolina, South Carolina, Tennessee
  • 5 = Indiana, Kentucky, Ohio, West Virginia
  • 6 = Illinois, Michigan, Wisconsin
  • 7 = Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota, Wyoming
  • 8 = Arkansas, Louisiana, New Mexico, Oklahoma, Texas
  • 9 = Alaska, Arizona, California, Idaho, Montana, Nevada, Oregon, Utah, Washington
  • 0 = When the first number is 3, the zero means he was drafted outside the U.S. (301 indicates Panama; 302 indicates Puerto Rico)

See if you can locate your ancestors’ serial number or their ‘dog tags’.

Photos: Collection of a soldier’s ID and a ‘dog tag’.

Related Blogs:

US Army Heritage and Education Center

US Army Wives 1865-1900

Military Pension Records

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