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.
Postage stamps and postal history of Guam
Following the victory of the United States in the war of 1898, in December 1898 Spain agreed by the treaty of Paris to sell the island of Guam, while the others Mariana islands became part of the German Empire. US troops had been present since an invasion the previous June.