General Requirements for Acquisition of Citizenship at Birth. A person born in the United States who is subject to the jurisdiction of the United States is a U.S. citizen at birth, to include a child born to a member of an Indian, Eskimo, Aleutian, or other aboriginal tribe.

Eligibility for citizenship through birth is primarily determined by two legal principles: Jus Soli (Right of Soil) and Jus Sanguinis (Right of Blood). Under Jus Soli, any individual born within the physical territory of a country is automatically granted citizenship, regardless of the parents' nationality. This is the standard in roughly 30 countries, most notably the United States, Canada, Mexico, and Brazil. In these nations, being born on a ship or plane registered to the country or within its territorial waters also counts. Conversely, most countries in Europe, Asia, and Africa follow Jus Sanguinis, where citizenship is granted only if at least one parent is already a citizen of that country at the time of birth. In 2026, some countries have "modified" Jus Soli rules; for example, in the UK or Australia, a child born there only gets citizenship if at least one parent is a citizen or permanent resident. These laws are complex and subject to change, often influenced by national immigration policies and international treaties regarding "stateless" persons.