Section H – Service Department Organizational Structures and Service Number Assignments

Updated Jun 24, 2022

In This Section

This section contains the following topics:

Topic	Topic Name
1	Army Organizational Structure
2	Navy Organizational Structure
3	Air Force Organizational Structure
4	Marine Corps Organizational Structure
5	Guide for Service Numbers 1 through 9,999,999
6	Guide for Service Numbers 10,000,000 through 19,999,999
7	Guide for Service Numbers 20,000,000 and Higher

1. Army Organizational Structure

Introduction

This topic contains information on the Army organizational structure, including

Change Date

December 13, 2005

III.ii.2.H.1.a. Army Echelons and Appropriate Designations

The table below lists the Army echelons and appropriate designations.

Echelons	Designations
Army	Numerical/Geographical
Corps	Roman numeral
Division	Numerical by combat arm
Brigade	Numerical or combat command, such as Alpha
Regiment	Numerical by combat arm
Group	Numerical by combat arm
Battalion	Numerical/battle group numerical/squadron numerical
Company	Alpha/Battery – Alpha/Troop – Alpha
Platoon	Numerical/Detachment – Numerical
Squad	Numerical
Fire Team	—

III.ii.2.H.1.b. Availability of Organizational Records

Rosters, morning reports, and sick reports may be available down to the company level.

Note: The Army discontinued morning reports in 1974/1975.

III.ii.2.H.1.c. Other Organizational Units that May Have Created Records

Records, including clinical and medical records, may exist for other organizations and units, such as

garrison-type units, and
hospitals.

Important: If a unit was considered independent from higher echelons, it may have created its own records.

2. Navy Organizational Structure

Introduction

This topic contains information on the Navy organizational structure, including

Navy echelons and appropriate designations
echelons for the
ship designations, and
shore establishment organization.

Change Date

August 13, 2009

III.ii.2.H.2.a. Navy Echelon and Appropriate Designations

The table below lists the Navy echelon and appropriate designations. For clarification, samples of unit designations are shown in italics.

Echelon	Designations
Fleet-Atlantic Pacific	Numbered fleets
Fleet	Numerical (7^th Fleet; 7thFlt.)
Task force	Task force number and type of force (CTF-45 Battle Force) *Notes*: Task forces are operational sub-units of fleets organized to perform specific missions for the fleet. The following are Naval Task forces: the Naval Air Force the Naval Surface Force, and the Naval Submarine Force.
Fleet Marine Force	*Reference*: For more information on the Fleet Marine Force, see M21-1, Part III, Subpart ii, 2.H.4.
U.S. Naval Forces Europe	—
Middle East Force-Persian Gulf	—

III.ii.2.H.2.b. Echelon for the Naval Air Force

The following list shows the echelon for the Naval Air Force:

carrier strike group (CSG 5)
carrier air wing, and (CVW-2)
squadron (VFA-2; VAQ-131)

Notes:

Carrier strike groups were historically designated carrier battle groups.
Carrier air wings were historically designated carrier air groups.

III.ii.2.H.2.c. Echelon for the Naval Surface Force

The following list shows the echelon for the Naval Surface Force:

flagship, and
Cruiser Destroyer Group Squadron (CCDG-5; DESRON-23)

Note: The Cruiser Destroyer Group Squadron consists of the Surface Group, Service Group Squadron, Amphibious Group Squadron, Mine Group Division, and Special Warfare Group.

III.ii.2.H.2.d. Echelon for the Naval Submarine Force

The following list shows the echelon for the Naval Submarine Force:

submarine group, and
submarine squadron (SUBRON 11)

III.ii.2.H.2.e. Ship Designations

Individual ships under the above echelons are identified as USS (name of ship) followed by an alpha-numerical hull number which

distinguishes the ship from other ships with the same name that may have preceded or may have followed it, and
identifies the type of ship.

Example: USS Independence CVA-62.

III.ii.2.H.2.f. Shore Establishment Organization

Shore establishments, such as non-moveable shore installations, were organized as bureaus (technical in nature) that, with the exception of personnel and medicine and surgery, became the Naval material command in 1963.

Other system type commands have followed this tradition.

3. Air Force Organizational Structure

Introduction

This topic contains information on the Air Force organizational structure, including

Change Date

December 13, 2005

III.ii.2.H.3.a. Air Force Echelon and Appropriate Designations

The table below lists the echelon of Air Force units and appropriate designations.

Units	Designations
Command	Geographical/specified mission
Air force	Numerical/geographical
Air Division	Numerical
Wing	Numerical/specified mission
Group	Numerical/specified mission
Squadron	Numerical/specified mission/alpha
Flight	Numerical—Alpha

III.ii.2.H.3.b. Availability of Organizational Records

Other organizational records may be available, such as

medical records
rosters
morning reports
courts martial, and
academic records.

Notes:

Some records may have a limited retention period.
Academic records dated after 1967 may be obtained from another National Archives and Records Administration center, if still retained.
Morning reports were discontinued in June 1966.

III.ii.2.H.3.c. Other Organizational Units That May Have Created Records

Records, including clinical and medical records, may exist for other organizations and units, such as

agency center
hospital
office
service, and
academy.

4. Marine Corps Organizational Structure

Introduction

This topic contains information on the Marine Corps organizational structure, including

Change Date

January 5, 2017

III.ii.2.H.4.a. Marine Corps Echelons and Appropriate Designations

The table below lists the Marine Corps echelons and appropriate designations. For clarification, samples of unit designations are shown in italics.

Echelon	Designation
Fleet Marine Force	Atlantic/Pacific (FMFPac)
Marine Amphibious Force *Note*: Consists of the Marine Division Marine Aircraft Wing, and Marine Logistics Group historically, Force Service Support Group, and counterpart, Marine Wing Support Group.	Roman numeral (I MAF) (operational)
Division *Note*: Major sub-elements consist of regiments, and battalions.	Numerical (3rdMarDiv) *Reference*: For more information on the echelons of a division, see M21-1, Part III, Subpart ii, 2.H.4.b.
Wing *Note*: Major sub-elements consist of groups, and squadrons.	Numerical (1stMAW) *Note: Squadrons are designated alpha-numerically. (VMA-211; HMM-262*)
Marine Expeditionary Force (MEF) *Note*: Marine Air ground task force for operations and exercises which consists of the Marine Division Marine Aircraft Wing, and Marine Logistics Group.	Roman numeral (III MEF)
Marine Expeditionary Brigade (MEB) *Note*: Marine Air ground task force for operations and exercises which consists of the Regimental Landing Team Composite Aircraft Group, and Combat Logistics Regiment.	Numerical (3d MEB)
Marine Expeditionary Unit (MEU) *Note*: Marine Air ground task force for operations and exercises which consists of the Battalion Landing Team Composite Aircraft Squadron, and Combat Logistics Battalion	Numerical (31 MEU)

Notes:

Expeditionary units replaced historically designated amphibious units.
Logistics units replaced historically designated force service support units.

III.ii.2.H.4.b. Division Echelons

The table below lists the Marine Corps division echelons and appropriate designations.

Echelon	Designation
Regiment	Numerical (7^th Marines; 7^th Mar.)
Battalion	Numerical (2^nd Battalion; 2^nd Bn)
Company	Alpha or phonetic (D Company; Delta Co.)
Platoon	Numerical (1^st Platoon; 1^st Plt.)
Squad	Numerical (3^rd Squad; 3^rd Sqd.)

III.ii.2.H.4.c. Availability of Organizational Records

The organizational records listed below are available for the years shown.

Muster rolls are available for the years 1801 through present.
Indexes are available for the years 1897 through 1939.
Unit diaries are available for the years 1949 through 1964.
Bound diaries are available back to 1901.

Notes:

Unit diaries have been microfilmed and are stored on the 5^th floor of the National Personnel Records Center (NPRC). These unit records may include
- command chronologies
- operational situation reports (sitreps), and
- operation after-action reports.
Some individual reels may be unusable due to poor storage conditions.
Marine Corps headquarters maintains duplicate copies of the unit diaries.
Many Marine Corps unit records are stored on compact discs (CDs) and accessed via the Stressor Verification page.

Reference: For more information on accessing these records, see

the Veterans Benefits Administration broadcast transcripts of
- December 17, 2003, “Researching Marine Corps Records,” and
- May 18, 2004, “C&P Military Records Research Information,” and
M21-1, Part III, Subpart ii, 2.E.6.d.

5. Guide for Service Numbers 1 through 9,999,999

Introduction

This topic contains a guide to service numbers 1 through 9,999,999, including

Change Date

July 23, 2018

III.ii.2.H.5.a. Army Service Numbers

The table below lists the numbers used for Army enlisted personnel for the periods shown.

Notes:

The Army originally assigned Air Force service numbers lower than 10,000,000.
Omitted blocks of numbers were not assigned.

Series	Dates Assigned
1 through 5,999,999	1918 through 1919
6,000,000 through 7,999,999	1919 through 1940
8,000,000 through 8,999,999	1948 and after (for Women only)

III.ii.2.H.5.b. Navy Service Numbers

The table below lists the numbers used for Navy enlisted personnel for the periods shown.

Series	Dates Assigned
1,000,000 through 1,999,999	1885-1918
2,000,000 through 9,999,999	1918-1965
100,000 and higher (Letter Prefix)	1965 and after

III.ii.2.H.5.c. Marine Corps Service Numbers

The table below lists the numbers used for Marine Corps enlisted personnel for the periods shown.

Series	Dates Assigned
20,000 through 99,999	1905 through 1917
100,000 through 349,999	1917 through 1941
350,000 through 670,899	1941 through 1947
700,000 through 799,999	reserved for female enlisted personnel only
800,000 through 999,999	1943 through 1947
1,000,000 through 1,699,999	1944 through 1957
1,700,000 through 1,799,999	reserved for female enlisted personnel only
1,800,000 through 1,999,999	1956 through 1965
2,000,000 and higher	1964 and after

III.ii.2.H.5.d. Coast Guard Service Numbers

The table below lists the numbers used for Coast Guard enlisted personnel for the periods shown.

Series	Dates Assigned
100,000 through 199,999	through 1930
200,000 through 254,999	1930 through 1942
255,000 through 349,999	1945 through 1962
350,000 through 499,999	1962 until 1974
500,000 through 999,999	1941 through 1945
2,000,000 through 2,199,999	1948 through 1974

6. Guide for Service Numbers 10,000,000 through 19,999,999

Change Date

December 13, 2005

III.ii.2.H.6.a. Regular Army and Regular Air Force Enlisted Service Numbers

The table below lists the numbers used for regular Army and regular Air Force enlisted personnel for the periods shown.

Notes:

Series 10,000,000 through 10,999,999 are used for initial enlistments occurring outside the continental limits.
The Army originally assigned Air Force service numbers lower than 10,000,000.

Series	Dates Assigned
10,000,000 through 10,999,999	1940 and after
11,000,000 through 11,142,500	1940 through 1945
11,142,501 through 11,188,000	1946 through 1948
11,188,001 through 11,238,500	1949 through 1951
11,238,501 through 11,283,000	1952 through 1954
11,283,001 through 11,344,500	1955 through 1957
11,344,501 through 11,384,000	1958 through 1960
11,384,001 through 11,999,999	1961 and after
12,000,000 through 12,242,000	1940 through 1945
12,242,001 through 12,321,000	1946 through 1948
12,321,001 through 12,393,500	1949 through 1951
12,393,501 through 12,469,000	1952 through 1954
12,469,001 through 12,553,375	1955 through 1957
12,553,376 through 12,614,900	1958 through 1960
12,614,901 through 12,999,999	1961 and after
13,000,000 through 13,197,500	1940 through 1945
13,197,501 through 13,299,700	1946 through 1948
13,299,701 through 13,408,700	1949 through 1951
13,408,701 through 13,511,500	1952 through 1954
13,511,501 through 13,621,140	1955 through 1957
13,621,141 through 13,705,500	1958 through 1960
13,705,501 through 13,999,999	1961 and after
14,000,000 through 14,204,500	1940 through 1945
14,204,501 through 14,300,770	1946 through 1948
14,300,771 through 14,454,000	1949 through 1951
14,454,001 through 14,547,500	1952 through 1954
14,547,501 through 14,661,000	1955 through 1957
14,661,001 through 14,745,000	1958 through 1960
14,745,001 through 14,999,999	1961 and after
15,000,000 through 15,201,000	1940 through 1945
15,201,001 through 15,280,500	1946 through 1948
15,280,501 through 15,465,760	1949 through 1951
15,465,761 through 15,530,600	1952 through 1954
15,530,601 through 15,593,615	1955 through 1957
15,593,616 through 15,639,615	1958 through 1960
15,639,616 through 15,999,999	1961 and after
16,000,000 through 16,201,500	1940 through 1945
16,201,501 through 16,307,000	1946 through 1948
16,307,001 through 16,398,890	1949 through 1951
16,398,891 through 16,481,925	1952 through 1954
16,481,926 through 16,600,497	1955 through 1957
16,600,498 through 16,638,100	1958 through 1960
16,683,101 through 16,999,999	1961 and after
17,000,000 through 17,183,500	1940 through 1945
17,183,501 through 17,254,500	1946 through 1948
17,254,501 through 17,338,810	1949 through 1951
17,338,841 through 17,410,300	1952 through 1954
17,410,301 through 17,512,785	1955 through 1957
17,512,786 through 17,592,940	1958 through 1960
17,592,941 through 17,999,999	1961 and after
18,000,000 through 18,247,100	1940 through 1945
18,247,101 through 18,360,800	1946
18,360,801 through 18,546,000	1947 through 1957
18,546,001 through 18,607,725	1958 through 1960
18,607,726 through 18,999,999	1961 and after
19,000,000 through 19,235,500	1940 through 1945
19,235,501 through 19,324,485	1946 through 1948
19,324,486 through 19,420,000	1949 through 1951
19,420,001 through 19,520,770	1952 through 1954
19,520,771 through 19,590,665	1955 through 1957
19,590,666 through 19,597,661	1958
19,597,662 through 19,999,999	1959 and after

7. Guide for Service Numbers 20,000,000 and Higher

Change Date

December 13, 2005

III.ii.2.H.7.a. Service Numbers 20,000,000 and Higher

The table below lists the service numbers 20,000,000 and higher, the time periods in which they were issued, and the service categories to which they were issued.

Series	Period Issued	Service Category
20,000,000 through 20,999,999	1940 through 1946	Enlisted National Guard in active duty.
21,000,000 through 29,999,999	1946 and after	Enlisted National Guard of the U.S.
30,000,000 through 39,999,999	1940 through 1946	Enlisted personnel inducted into the Army of the U.S.
40,000,000 through 41,999,999	—	Apparently not used or allocated.
42,000,000 through 46,999,999	1943 through 1946	Enlisted personnel inducted into the Army of the U.S.
47,000,000 through 49,999,999	—	Apparently not used or allocated.
50,000,000 through 59,999,999	1948 through 1966	Army and Air Force Emergency Interim Issue (EM). *Note*: Regular Army and Air Force are not included.
60,000,000 through 69,999,999	1966 and after	Army and Air Force EM. *Note*: Regular Army and Air Force are not included.
70,000,000 through 89,999,999	—	Apparently not used or allocated.
90,000,000 through 99,999,999	1940 through 1945	Only a limited number, about 20,000 within this series, were used for the Philippine Army during World War II. *Note*: There is no evidence of other usage.

38 CFR Part 3 (Click to Open)

38 CFR Part 4 (Click to Open)

VA Disability Codes [Click to Expand]

M21-1 Table of Contents

M21-5 Table of Contents

In This Section

1. Army Organizational Structure

Introduction

Change Date

III.ii.2.H.1.a. Army Echelons and Appropriate Designations

III.ii.2.H.1.b. Availability of Organizational Records

III.ii.2.H.1.c. Other Organizational Units that May Have Created Records

2. Navy Organizational Structure

Introduction

Change Date

III.ii.2.H.2.a. Navy Echelon and Appropriate Designations

III.ii.2.H.2.b. Echelon for the Naval Air Force

III.ii.2.H.2.c. Echelon for the Naval Surface Force

III.ii.2.H.2.d. Echelon for the Naval Submarine Force

III.ii.2.H.2.e. Ship Designations

III.ii.2.H.2.f. Shore Establishment Organization

3. Air Force Organizational Structure

Introduction

Change Date

III.ii.2.H.3.a. Air Force Echelon and Appropriate Designations

III.ii.2.H.3.b. Availability of Organizational Records

III.ii.2.H.3.c. Other Organizational Units That May Have Created Records

4. Marine Corps Organizational Structure

Introduction

Change Date

III.ii.2.H.4.a. Marine Corps Echelons and Appropriate Designations

III.ii.2.H.4.b. Division Echelons

III.ii.2.H.4.c. Availability of Organizational Records

5. Guide for Service Numbers 1 through 9,999,999

Introduction

Change Date

III.ii.2.H.5.a. Army Service Numbers

III.ii.2.H.5.b. Navy Service Numbers

III.ii.2.H.5.c. Marine Corps Service Numbers

III.ii.2.H.5.d. Coast Guard Service Numbers

6. Guide for Service Numbers 10,000,000 through 19,999,999

Change Date

III.ii.2.H.6.a. Regular Army and Regular Air Force Enlisted Service Numbers

7. Guide for Service Numbers 20,000,000 and Higher

Change Date

III.ii.2.H.7.a. Service Numbers 20,000,000 and Higher

Related M21 References

M21-1 Table of Contents

M21-5 Table of Contents