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.
United States territory
The fifty states, the District of Columbia, and Puerto Rico form the main customs territory of the United States. Special rules apply to foreign trade zones in these areas. Separate customs territories are formed by American Samoa, Guam, Northern Mariana Islands, the U.S. Minor Outlying Islands, and the U.S. Virgin Islands.