The United States does permit its citizens to hold one or more additional nationalities, but U.S. law imposes strict rules on how a dual‑national must travel in and out of the country.
Dual citizenship is legal in the United States
- U.S. law does not forbid a person from acquiring another passport after naturalisation.
- Most foreign governments also allow their citizens to keep their original nationality when they become American (e.g., Nigeria, Poland).
- A few countries—most notably China—require renunciation of their citizenship before granting a new one.
Travel requirements for U.S. citizens
- Entry and departure: When you are a U.S. citizen you must present a U.S. passport at every U.S. port of entry and exit. This is the same rule that applies in most other nations.
- Using a foreign passport: A second passport (e.g., St. Lucian, Portuguese) cannot be used to enter the United States, nor can it be used to obtain a U.S. visa while you remain a U.S. citizen.
- Visa‑waiver program: Citizens of the roughly 40 countries that participate in the Visa Waiver Program must still travel on their U.S. passport when crossing U.S. borders, even if they hold another passport that would otherwise allow visa‑free entry.
Why the rule exists
The U.S. government wants to ensure that anyone arriving on U.S. soil is treated as a U.S. citizen for legal and consular purposes. Allowing entry on a foreign passport could create situations where a person seeks assistance from another country’s embassy while still subject to U.S. law, as seen in cases involving dual‑national Iranian‑Americans or Russian‑Americans.
Practical implications
- Second passport as insurance: Holding an additional passport can be valuable for travel, business, or future renunciation of U.S. citizenship, but it does not change the requirement to use a U.S. passport for U.S. border crossings.
- Leaving the United States: To depart the U.S. on a foreign passport you would first need to relinquish U.S. citizenship and obtain any necessary visas in the new passport.
- Planning travel: When arranging trips that involve both U.S. and non‑U.S. destinations, schedule entry and exit from the United States with your U.S. passport, and use your second passport only for travel to countries where it offers an advantage.
In summary, U.S. citizens may legally hold dual citizenship, but the United States mandates the use of a U.S. passport for all entries and exits, limiting the functional use of a second passport while residing in or traveling through the United States.
