An insular area is a United States territory, that is neither a part of one of the 50 U.S. states nor the District of Columbia, the federal district of the U.S. They are called "insular" from the Latin word insula ("island") because they were once administered by the War Department's Bureau of Insular Affairs, now the Office of Insular Affairs at the Department of the Interior. The term insular possession is also sometimes used.

Because those insular areas that are inhabited are unincorporated territories, their native-born inhabitants are not constitutionally entitled to United States citizenship, under the Citizenship Clause.^{[citation needed]} However, Congress has extended citizenship rights to all inhabited territories except American Samoa, and these citizens may vote and run for office in any U.S. jurisdiction in which they are residents. The people of American Samoa are U.S. nationals, but not U.S. citizens; they are free to move around and seek employment within the whole United States without immigration restrictions, but cannot vote or hold office outside of American Samoa.^{[citation needed]}