Guam is organized as an unincorporated territory of the United States as the President Harry S. Truman signs the Guam Organic Act.

Guam is an island that is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. Guam's capital is Hagåtña, and the most populous village is Dededo. It is the westernmost point and territory of the United States, as measured from the geographic center of the U.S. In Oceania, Guam is the largest and southernmost of the Mariana Islands and the largest island in Micronesia. In 2022, its population was 168,801. Chamorros are its largest ethnic group, but a minority on the multiethnic island. The territory spans 210 square miles and has a population density of 775 per square mile (299/km²).

Harry S. Truman was the 33rd president of the United States, serving from 1945 to 1953. As the 34th vice president in 1945, he assumed the presidency upon the death of Franklin D. Roosevelt that year. Subsequently, Truman implemented the Marshall Plan in the aftermath of World War II to rebuild the economy of Western Europe, and established both the Truman Doctrine and NATO to contain the expansion of Soviet communism. A member of the Democratic Party, he proposed numerous New Deal coalition liberal domestic reforms, but few were enacted by the conservative coalition that dominated the United States Congress.

The Guam Organic Act of 1950, is a United States federal law that redesignated the island of Guam as an unincorporated territory of the United States, established executive, legislative, and judicial branches, and transferred federal jurisdiction from the United States Navy to the United States Department of the Interior. For the first time in over three hundred years of foreign colonization, the people of Guam had some measure of self-governance, however limited. Before that time there was some participation in the Local Administration, through the mayors or "gobernadorcillos" in Spanish times, who acted under the supervision of the Governor of the Mariana Islands.