The
United States of America maintains
sovereignty over a number of
islands, mostly found in the
Pacific Ocean and
Carribean Sea.
Guam, the Virgin Islands, and American Samoa are its major Territories while Puerto Rico and the Northern Mariana Islands make up its principal Commonwealths. Many other tiny islands are considered simple possessions of the United States.
In his article entitled, The Overseas Territories and Commonwealths Of the United States of America1, Attorney at Law Dan MacMeekin makes the excellent point that only a U.S. Citizen residing in a State is entitled to vote for the President of the United States, Senators or Representatives in the House of Representatives.
Mr. MacMeekin also notes that until the early 20th century, gaining territorial status was a stepping stone to Statehood -- this stopped with the acquisition of Cuba, Puerto Rico, the Philippine Islands and Guam in the Spanish American War. Since territories are no longer intended for Statehood, he says, any justifications for treating them as inferior jurisdictions disappear.
The American consensus seems to be that, although Citizens living outside the fifty States are unable to vote, they also don't have to pay federal taxes. It's also commonly suggested that residents of Territories or possessions don't desire Statehood, although aside from a series of public referendums there's really no way to say.
1 Dan MacMeekin's article is available online from:
http://www.macmeekin.com/Library/terr+commonw2.htm