| Year | Admission Method | Territory/Treaty | % Correct |
|---|---|---|---|
| 1867 | Treaty purchasing land | Alaska | Alaska Purchase | 92%
|
| 1819 | Treaty trading land/defining border | Florida | Adams-Onís Treaty | 92%
|
| 1898 | Joint resolution of Congress | Hawaii | Newlands Resolution | 92%
|
| 1803 | Treaty purchasing land | Louisiana Territory | Louisiana Purchase | 92%
|
| 1898 | Treaty ending war | Puerto Rico | Treaty of Paris | 83%
|
| 1845 | Joint resolution of Congress | Texas | Joint Resolution for Annexing Texas | 83%
|
| 1791 | Congressional act | Vermont | Vermont Admission Act | 75%
|
| 1846 | Treaty defining border | Oregon Territory | Oregon Treaty | 58%
|
| 1607–1732 | Various charters and conquests | Thirteen Colonies | 58%
|
| 1783 | Treaty recognizing USA/ending war | Western Territory | Treaty of Paris | 42%
|
| 1853–54 | Treaty purchasing land | Gadsden Purchase | 33%
|
| 1848 | Treaty ending war | Mexican Cession | Treaty of Guadalupe Hidalgo | 17%
|
| 1842 | Treaty defining border | Aroostook Region + 1 | Webster-Ashburton Treaty | 8%
|
| 1818 | Treaty defining border | British Cession | Treaty of 1818 | 8%
|
| 1819 | Treaty trading land/defining border | West Florida + 2 | Adams-Onís Treaty | 0%
|