51st state
Guam (formally the Territory of Guam) is an unincorporated and organized territory of the United States. Located in the western Pacific Ocean, Guam is one of five American territories with an established civilian government.
List of U.S. states and territories by income
The District of Columbia and the inhabited U.S. territories (Puerto Rico, the U.S. Virgin Islands, Guam, the Northern Mariana Islands and American Samoa) are not formally US states, but their residents are American citizens (except for American Samoa — people born in American Samoa are non-citizen U.S. nationals). Puerto Rico has a higher population than 21 US states, while D.C. has a higher population than 2 states.