The United States military has at least 750 bases in 80 countries around the world. The largest proportion of these, of course, are in the 50 states. After this, the biggest share of American military installations are in Europe, followed by Southeast Asia, including Camp Humphreys in South Korea. While Camp Humphreys, built in 1950, is the largest U.S. military base in a foreign country, it is far from the oldest.
To determine the oldest U.S. active military bases that are overseas, 24/7 Wall St. reviewed the study, U.S. Military Bases Abroad, 1776-2021 by David Vine, professor at the department of anthropology at American University. We ranked the bases according to the year they opened, listing the 23 bases founded by 1943 at the latest. Data on the number of active-duty personnel and bases within each country as well as estimated land acreage of each base came from the Quincy Institute for Responsible Statecraft, a military think-tank.
Out of the 23 bases on the list, 13 are located in Puerto Rico, operated by the Army, Navy, and Air Force. Not surprising given the important strategic position Puerto Rico holds between the Caribbean Sea and the Atlantic Ocean. The first of these was constructed in 1902. (Also see, the six European bases where the U.S. is storing nuclear bombs.)
Puerto Rico was one of the territories the United States received in the wake of its victory over Spain in the Spanish-American War in 1898. Cuba, which gained independence from Spain following that war, agreed to lease Guantánamo Bay to the U.S. Navy on its southeastern shore in 1903. Other possessions the U.S. secured from Spain in the Pacific – Guam and Wake Island – have military bases.
Elsewhere, four of the oldest U.S. overseas bases are in the United Kingdom, established there just after America entered the war in 1941. That same year, the U.S. began leasing from Denmark the Thule Air Base in Greenland, which at more than 233,000 acres, is by far the largest overseas military base by physical size. (This is the largest military base in each state.)
Click here to see the oldest international military bases.
Source: Public Domain / Wikimedia Commons
23. RAF Welford Ammo Storage Area, United Kingdom
> Opening year: 1943
> Location: Oxfordshire, United Kingdom
> Active duty personnel in country: 10,770
> US bases in country: 25 — #7 most out of 80
> Land estimated acreage: 736 acres
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22. RAF Feltwell, United Kingdom
> Opening year: 1942
> Location: Thetford, United Kingdom
> Active duty personnel in country: 10,770
> US bases in country: 25 — #7 most out of 80
> Land estimated acreage: 305 acres
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Source: cne-cna-c6f / Flickr
21. RAF Molesworth, United Kingdom
> Opening year: 1942
> Location: Molesworth, United Kingdom
> Active duty personnel in country: 10,770
> US bases in country: 25 — #7 most out of 80
> Land estimated acreage: 696 acres
Source: usairforce / Flickr
20. RAF Alconbury, United Kingdom
> Opening year: 1942
> Location: Great Stukeley, United Kingdom
> Active duty personnel in country: 10,770
> US bases in country: 25 — #7 most out of 80
> Land estimated acreage: 218 acres
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Source: Public Domain / Wikimedia Commons
19. Cabeza De Perro, Puerto Rico
> Opening year: 1942
> Location: Ceiba, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 29 acres
Source: arcticwarrior / Flickr
18. Wake Island Airfield, Wake Island
> Opening year: 1941
> Location: Wake Island
> Active duty personnel in country: 2,600
> US bases in country: 1 — #50 most out of 80 (tied)
> Land estimated acreage: 5 acres
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17. Vieques West, Puerto Rico
> Opening year: 1941
> Location: Vieques, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 275 acres
16. Mount Pirata, Puerto Rico
> Opening year: 1941
> Location: Mayaguez, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 59 acres
Source: Public Domain / Wikimedia Commons
15. Roosevelt Rds Naval Station USARC, Puerto Rico
> Opening year: 1941
> Location: Ceiba, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 29 acres
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14. Luis Munoz Marin IAP, Puerto Rico
> Opening year: 1941
> Location: Carolina, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 95 acres
Source: Public Domain / Wikimedia Commons
13. Fort Allen, Puerto Rico
> Opening year: 1941
> Location: Juana, Diaz, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 117 acres
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Source: MortenChr / iStock via Getty Images
12. Thule Greenland, Greenland (Denmark)
> Opening year: 1941
> Location: North Star Bay, Greenland
> Active duty personnel in country: 147
> US bases in country: 1 — #50 most out of 80 (tied)
> Land estimated acreage: 233034 acres
Source: Public Domain / Wikimedia Commons
11. Argentia Newfoundland, Canada
> Opening year: 1941
> Location: Newfoundland and Labrador, Canada
> Active duty personnel in country: 185
> US bases in country: 3 — #34 most out of 80 (tied)
> Land estimated acreage: 161 acres
Source: Public Domain / Wikimedia Commons
10. MTA Camp Santiago, Puerto Rico
> Opening year: 1940
> Location: San Juan, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 14650 acres
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Source: demerzel21 / iStock via Getty Images
9. Salinas N00207, Puerto Rico
> Opening year: 1940
> Location: Salinas, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 249 acres
Source: alexandra oquendo / iStock via Getty Images
8. Aguadilla, Puerto Rico
> Opening year: 1936
> Location: Aguadilla, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 0 acres
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Source: Public Domain / Wikimedia Commons
7. Johnston Atoll Airfield, Johnston Atoll
> Opening year: 1934
> Location: Johnston Atoll
> Active duty personnel in country: 00
> US bases in country: 1 — #50 most out of 80 (tied)
> Land estimated acreage: 684 acres
Source: Public Domain / Wikimedia Commons
6. Fort Buchanan, Puerto Rico
> Opening year: 1923
> Location: Guaynabo City, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 1635 acres
5. AMSA 161, Puerto Rico
> Opening year: 1923
> Location: Guaynabo City, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 0 acres
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Source: Courtesy of ArmyReserve/1st MSC via Facebook
4. CPT Euripides Rubio Jr. USARC, Puerto Rico
> Opening year: 1922
> Location: Puerto Nuevo, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 63 acres
Source: usnavy / Flickr
3. Guantanamo Bay, Cuba
> Opening year: 1903
> Location: Guantanamo, Cuba
> Active duty personnel in country: 1,004
> US bases in country: 1 — #50 most out of 80 (tied)
> Land estimated acreage: 28817 acres
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Source: gionnixxx / iStock via Getty Images
2. Mayaguez, Puerto Rico
> Opening year: 1902
> Location: Mayaguez, Puerto Rico
> Active duty personnel in country: 13,571
> US bases in country: 34 — #6 most out of 80
> Land estimated acreage: 0 acres
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Source: sdasmarchives / Flickr
1. Agana, Guam
> Opening year: 1899
> Location: Apra Harbor, Guam
> Active duty personnel in country: 11,295
> US bases in country: 54 — #4 most out of 80
> Land estimated acreage: 22 acres
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