The U.S. has held more possessions (outside of the contiguous U.S.) than most people realize. I couldn't find a single convenient listing of territories, so I did a bit of research and put this together. While it's not complete, it is fairly extensive. I've tried to find two sources for everything I've added, but there still may be a few errors.
| Claimed | Until | Name | Notes | Present Status |
|---|---|---|---|---|
| 1821 | 1847 | Liberia | The Society for the Colonization of Free People of Color of America | independent |
| 1822? | 1983 | Danger, Manahiki, Penrhyn, Rakahanga | no official claim? | U.S. recognized as part of the Cook Islands |
| 1841? | 1983 | Atafu, Fafaofu, Nukumono | no official claim? | U.S. recognized as part of Tokelau, New Zealand |
| c. 1856 | 1981 | Serrana Bank | Guano Islands Act | ceded to Colombia |
| c. 1856 | 1981 | Roncador Bank | Guano Islands Act | ceded to Colombia |
| c. 1856 | 1983 | Line Islands | Guano Islands Act | all except Kingman Reef/Palmyra Atoll/Jarvis Island ceded to Kiribati |
| c. 1856 | 1983 | Phoenix Islands | Guano Islands Act, shared with the U.K. | all except Baker and Howland ceded to Kiribati |
| 1856 | present | Swains Island | received title from U.K.? | administered as part of American Samoa, disputed Tokelau NZ |
| 1857 | present | Baker Island | Guano Islands Act | unincorporated unorganized territory |
| 1857 | present | Jarvis Island | Guano Islands Act, annexed by U.K. 1889-1935 | unincorporated unorganized territory |
| 1857 | present | Navassa Island | Guano Islands Act | unincorporated unorganized territory, disputed Haiti and others |
| 1857 or 1858 | present | Howland Island | Guano Islands Act | unincorporated unorganized territory |
| 1858 | present | Johnston Atoll | Guano Islands Act, disputed Hawai'i | unincorporated unorganized territory |
| 1863 | 1972 | Swan Islands | Guano Islands Act | ceded to Honduras |
| 1867 | present | Midway Atoll (Midway Islands) | Guano Islands Act | unincorporated unorganized territory |
| 1867 | present | Alaska | purchased from Russia | state |
| 1869 | 1981 | Quita Sueño Bank | Guano Islands Act | ceded to Colombia |
| 1869 | present | Bajo Nuevo Bank (Petrel Islands) | Guano Islands Act | unincorporated unorganized territory, disputed Colombia, Honduras, Jamaica, Nicaragua |
| 1879 | present | Serranilla Bank | Guano Islands Act | unincorporated unorganized territory, disputed Colombia, Honduras, Jamaica, Nicaragua |
| 1898 | present | Hawai'i | Newlands Resolution | state |
| 1898 | present | Palmyra Atoll | aquired with Hawai'i, invalidly? claimed in 1859 under Guano Islands Act, annexed by U.K. 1889-1912 | incorporated unorganized territory |
| 1898 | 1902 | Cuba | Spanish-American War, Treaty of Paris | independent, except U.S. Guantánamo Bay Naval Base |
| 1898 | 1946 | Philippines | Spanish-American War, Treaty of Paris | independent |
| 1898 | present | Guam | Spanish-American War, Treaty of Paris | unicorporated organized territory |
| 1898 | present | Puerto Rico | Spanish-American War, Treaty of Paris | commonwealth |
| 1899 | present | American Samoa | Tripartite Convention with the U.K. and Germany/Prussia, Tutuila 1900/Manu'a 1904 | unincorporated unorganized but self-governing territory |
| 1898 or 1899 | present | Wake Island (Wake Atoll) | claimed during Spanish-American War | unincorporated unorganized but inhabited territory, disputed Marshall Islands |
| 1903 | 1979 | Panama Canal Zone | Hay-Bunau Varilla Treaty | ceded to Panama |
| 1906 | 1977 | Rio Rico | south of the Rio Grande after the river was diverted | ceded to Mexico |
| 1914 | 1971 | Corn Islands | Bryan-Chamorro Treaty, leased from Nicaragua | returned to Nicaragua |
| 1917 | present | U.S. Virgin Islands | purchased from Denmark | unincorporated organized territory |
| 1922 | present | Kingman Reef | invalidly? claimed under Guano Islands Act | unincorporated unorganized territory |
| 1944 | 1986 | Federated States of Micronesia | WWII, part of the Trust Territory of the Pacific Islands 1947-1979 | independent |
| 1944 | 1986 | Marshall Islands | WWII, TTPI 1947-1979 | independent |
| 1944 | 1994 | Palau | WWII, TTPI 1947-1981 | independent |
| 1944 | present | Northern Marianas Islands | WWII, TTPI 1947-1978 | commonwealth |
| 1945 | 1968 | Bonin Islands (Ogasawara Islands) | WWII, Treaty of San Francisco in 1952, U.S. claims as early as 1830 | returned to Japan |
| 1945 | 1972 | Ryukyu Islands (Nansei Islands) | WWII, Treaty of San Francisco in 1952 | returned to Japan |
| 1952 | 1968 | Minami Torishima (Marcus Island) | WWII, Treaty of San Francisco, U.S. claims as early as 1889 | returned to Japan |
Sources: