United States historical military districts

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U.S. military administration districts, departments, divisions

These entities were sometimes the only governmental authority in the listed areas, although they often co-existed with civil governments in scarcely populated states and territories.

  • From June 14, 1798 until May 14, 1800, Maj. Gen. Charles Cotesworth Pinckney commanded a district that encompassed Georgia, Tennessee, North Carolina, South Carolina and Virginia. Brig. Gen. James Wilkinson commanding troops in the remaining states in the north and west.


From May 14, 1800, the army was divided into 11 geographical districts, with an informal alignment into western and eastern departments. On February 15, 1809, the Army was reorganized into Northern, Southern, and Western Military Districts. In June 1810, the Southern and Western Districts were consolidated as the Southern Department, and the Northern District was designated Northern Department.

  • Defense of the City and Harbor of New York, 1812–13.
  • 4th Brigade of Detached Militia, 1812–13,
  • District of Oswego, Sackett's Harbor, and Ogdensburg, 1813


On March 19, 1813, during the War of 1812 the United States was divided into 9 numbered military districts. They were increased to 10 on July 2, 1814 and reduced to 9 by consolidation of the 4th and 10th Districts in January 1815.

  • 1st Military District, 1813–15
  • 2d Military District, 1814–15
  • 3d Military District, 1813–15
  • 4th Military District, 1813–14
  • 4th and 10th Military Districts (consolidated), 1815
  • 5th Military District, 1813–15
  • 6th Military Districts, 1813–15
  • 7th Military Districts, 1813–15
  • 9th Military District and Right Wing (1st Division), Northern Army (under unified command), 1814–15
  • Left Wing (2d Division), Northern Army, 1814
  • 10th Military District, 1814.


On May 17, 1815, the military districts were abolished, and superseded by 10 numbered Military Departments, divided equally between the Division of the North with 1st–5th Military Departments and Division of the South with the 6th–10th Military Departments.


In May 1821, the Divisions of the North and South and the Military Departments were abolished and the Army reorganized into Eastern and Western Departments. From time to time various departments or Armies appeared in the Western Department.

  • Western Department, 1821–37
    • Right Wing, Western Department, 1832–37
    • Army of the Frontier, 1832
    • 1st Army Corps, North West Army, 1832
    • Army of the Southwestern Frontier, 1834–37.
  • Eastern Department, 1821–37


In 1837 the Army returned to a system of Divisions with subordinate numbered Military departments. Between 1842 and 1844, the Divisions were abolished with only the Military Departments in operation.

  • Eastern Division, 1837–42
    • 7th Military Department, 1837–41
  • Western Division, 1837–42
    • 1st Military Department, 1837–42
    • 2nd Military Department, 1837–42
    • 7th Military Department, 1841–42
  • 1st Military Department, 1842–43
  • 2nd Military Department, 1843–51
  • 3rd Military Department, 1842–48
  • 4th Military Department, 1842–53
  • 5th Military Department, 1842–52
  • 8th Military Department, 1842–46
  • 9th Military Department, 1842–45 (Florida)


In 1844 the Army renewed the use of the Eastern and Western Divisions during the Mexican–American War.

  • Eastern Division, 1844–48
    • 5th Military Department, 1844–48
    • 8th Military Department, 1844–46
  • Western Division, 1844–48
    • 2nd Military Department, 1844–48
    • 3rd Military Departments, 1844–48
  • 4th Military Department, 1844–53
  • 9th Military Department, 1845 (Florida)
  • 10th Military Department, 1846 – 1853 (California and Oregon to 1848)


Following the Mexican war, the army reorganized to occupy the vast new territory acquired.

  • Eastern Division, 1848–53
    • 1st Military Department, 1848–53; consolidated 1st and 3d Military Departments, 1849–50
    • 2nd Military Department, 1848–51; consolidated 1st and 2d Military Departments, 1848–49
    • 3rd Military Departments, 1848, 1850–53
    • 4th Military Departments, 1848–53; consolidated 3d and 4th Military Departments, 1848
  • Western Division, 1848–53
    • consolidated 5th and 6th Military Departments, 1848
    • 5th Military Department, 1848–52
    • 6th Military Department, 1848–53
    • 7th Military Department, 1848–53
    • 8th Military Department, 1848–49, 1851–53
    • 9th Military Department, 1849–53 (New Mexico)
  • Pacific Division, 1848–53,(California and Oregon)
  • 10th Military Department, 1846 – 1853 (California and Oregon to 1848, California only 1848-1850)
  • 11th Military Department, 1848 – 1853 (Oregon)


After October 31, 1853 the division echelon was eliminated and the departments in the east became one Department of the East, administering all the territory east of the Mississippi River. The six western departments consolidated into four (Departments of Texas, New Mexico, the West, and the Pacific). The system returned to six departments in 1858 when the Department of Utah was created in January, and the Department of the Pacific split into the Departments of California and Oregon in September.

Eastern United States

Western United States

Pacific area

1861–1865 During the American Civil War the Eastern Department was eliminated, exploding into many Departments, districts and subdistricts of the Union Army.


Eastern United States

Southeastern United States

Western United States

Pacific area

Overseas regions primarily under U.S. military administration

See also


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