U.S. Citizenship by Birth or Through Parents

The question of who is a U.S. citizen based on their birth or their parents' citizenship is not as clearcut as it sounds. Many people become U.S. citizens automatically, despite having been born in another country, because they have direct ancestors who are (or were) U.S. citizens. They might not even realize they are citizens.

And some young people living in the United States with green cards become U.S. citizens when their parents apply for and receive citizenship.

In short, U.S. citizenship can be obtained in one of four ways:

• birth in the United States or one of its territories
• birth to U.S. citizen parents (called "acquisition" of citizenship)
• naturalization of one's parents (called "derivation" of citizenship), or
• naturalization (obtaining citizenship after an application and exam).

The last item on the list, naturalization after holding a green card (U.S. lawful permanent residence), is discussed in Who Can Apply for U.S. Citizenship. Below, we'll discuss the first three items on the list.

Why Some Foreign-Born People Don't Realize They Became U.S. Citizens at Birth

Most of the people who became U.S. citizens at birth but don't necessarily realize it fall into one of three groups:

• People born in the United States who have lived most of their lives in other countries. If you fall into this category, you might mistakenly believe that your long absence from the country, plus voting or military activities elsewhere, have stripped you of U.S. citizenship. This is likely not the case, as described in When U.S. Citizens Can Lose Their U.S. Citizenship.
• People who have U.S. citizens in their direct line of ancestry. If your parents or grandparents were U.S. citizens, you might not realize that U.S. citizenship got passed down the line, even if you were born elsewhere and your parents or grandparents haven't lived in the United States for a long time.
• Green-card holding children of naturalized U.S. citizens. When parents become naturalized U.S. citizens, their minor children with green cards gain U.S. citizenship automatically. (Especially handy because children under the age of 18 cannot normally apply to become naturalized U.S. citizens.)

You will, however, need to do some research to establish your citizenship rights. Here, we'll explore each of the above three possibilities in turn.

Birth in the United States or a U.S. Territory

By operation of the 14th Amendment to the U.S. Constitution, a child born on American soil and "subject to the jurisdiction" of the U.S. government is automatically a U.S. citizen. Children born in certain U.S. territories—Puerto Rico, the Virgin Islands, the Northern Marianna Islands, and Guam—may also acquire U.S. citizenship if at least one parent is a U.S. citizen and was physically present in the United States or one of its outlying possessions for a continuous period of one year at any time before the birth. For details, see Section 301 of the Immigration and Nationality Act.

Anyone born with U.S. citizenship retains it for life unless they deliberately give it up—for example, by filing an oath of renunciation.

This law has long been viewed as highly inclusive, with few and narrow exceptions. One of the biggest exceptions is for children born to foreign diplomatic officials in the United States. Because these officials are not considered to be subject to U.S. jurisdiction, any children they might bear here do not become citizens, though they may be granted green cards. (See 8 C.F.R. Section 101.3(a)(1).)

WARNING: In January of 2025, Donald Trump sought to add another exception to the law on birthright citizenship, by issuing an Executive Order (EO) stating that U.S. citizenship shall no longer be granted to U.S.-born children if either of the two following were true at the time of birth:

• the child's mother was unlawfully present in the United States (also called "undocumented" or "illegal") and the father was neither a U.S. citizen nor a lawful permanent resident, or
• the mother's presence in the United States was lawful but only temporary (perhaps because she was visiting the United States on the Visa Waiver Program or after being granted a student, work, or tourist visa, among other possibilities) and the father was neither a U.S. citizen nor a lawful permanent resident.

The theory behind this Trump order is that parents in the above situations are not subject to the jurisdiction of the United States. Numerous commentators disagree, noting that undocumented immigrants must follow U.S. laws, pay U.S. taxes, and so on. The matter quickly became the subject of lawsuits.

For starters, a federal judge in Seattle declared the move unconstitutional and blocked it pending further litigation. Then a district court judge in Maryland issued a similar order, as did another judge in New Hampshire. Also, the attorneys general of Massachusetts, New Jersey, and California brought together a coalition of 17 state attorneys general (AGs) to file suit in the U.S. District Court of Massachusetts, in response to which Federal Judge Leo Sorokin issued a preliminary injunction preventing the EO from taking immediate effect across the United States.

The issue made its way to the U.S. Supreme Court, in the case of Trump v. CASA, decided on June 27, 2025. The high Court didn't rule directly on whether birthright citizenship is constitutional. However, it left the door open for the Trump EO to come into effect, by saying that federal judges would be exceeding their power in issuing nationwide injunctions (or what the Court called "universal injunctions") in cases where a narrower order would provide complete relief to the plaintiffs. (Exactly what "complete relief means in this context could itself be a topic for further litigation.)

State AGs and immigrant advocates have since scrambled to develop new legal strategies to more broadly block the Trump EO. Class action lawsuits was the first approach tried, which on July 10, resulted in a federal judge in New Hampshire blocking Trump's order restricting birthright citizenship by certifying a nationwide class for purposes of a class-action lawsuit. The Trump order cannot take effect until the litigation is over. Assuming the New Hampshire judge eventually rules against the Trump order, we can expect birthright citizenship to be taken to the Supreme Court once again, this time on the merits of the matter.

An important thing to realize is that the Trump order was NOT written to be retroactive; in other words, children born to a mother who lacks immigration papers or is in the United States temporarily can safely be assumed to hold U.S. citizenship until the courts weigh in and an effective date is set. But this is certainly an unsettling time for families expecting to give birth in the United States.

Birth to U.S. Citizen Parents ("Acquisition")

In many circumstances, even though a child is born outside the United States, if at least one parent was a U.S. citizen at the time of the child's birth, the child automatically "acquires" citizenship. When this child marries and has children, those children may also acquire U.S. citizenship at birth.

The laws governing whether or not a child born outside of the United States acquires U.S. citizenship from parents have changed several times. For example, although during all periods they have required that at least one parent have spent time living in the United States, the exact time period varies from an unspecified amount to 10 years. In one bit of good news, USCIS clarified in a 2024 Policy Alert that even an undocumented person who later becomes a U.S. citizen can count their years with no immigration status toward this total.

You'll need to look at the law that was in effect on the date of the child's birth (and the parents' birth, if grandparents were U.S. citizens who might have passed it down to the parent) for guidance. These laws differ for the following time periods:

• prior to May 24, 1934
• May 25, 1934 to January 12, 1941
• January 13, 1941 to December 23, 1952
• December 24, 1952 to November 13, 1986, and
• November 14, 1986 to present.

To read about the law that was in effect at the time of your birth, see Automatic U.S. Citizenship for Children Born to or Adopted by Citizen Parents (Acquisition) or the book U.S. Immigration Made Easy, by Ilona Bray (Nolo).

Naturalization of Parents ("Derivation")

When a parent naturalizes, the children may "derive" U.S. citizenship automatically, provided they have green cards and are under age 18 and living with the parent at the time.

Becoming a U.S. citizen in this way has a special benefit: A child who gets U.S. citizenship through the naturalization of either or both parents does not have to participate in a naturalization ceremony.

The laws on the automatic naturalization of children have varied over the years. Whether or not you are a U.S. citizen is determined by the laws that existed when your parent's naturalization took place. These laws differ for the following time periods:

• parents who naturalized before May 24, 1934
• parents who naturalized between May 24, 1934 and January 12, 1941
• parents who naturalized between January 13, 1941 and December 23, 1952
• parents who naturalized between December 24, 1952 and October 4, 1978
• parents who naturalized between October 5, 1978 and February 26, 2001, and
• parents who naturalized between February 27, 2001 and the present.

To read about what law was in effect at the time of your parents' naturalization, see the book U.S. Immigration Made Easy, by Ilona Bray (Nolo).

Proving Your U.S. Citizenship

If you have a claim to U.S. citizenship based on one of the laws discussed in this article, you should acquire a passport or other document to prove it. To learn more, see Obtaining Proof of U.S. Citizenship.

Getting Legal Help

If you would like a personal analysis of whether you have derived or acquired U.S. citizenship, or you would help proving it, your best bet is to consult an experienced immigration attorney.