It is the legal process of becoming a citizen of a country you were not born into. The final step is an oath, taken by hundreds of thousands of people every year, that turns an immigrant into an American.
Naturalization is the way a foreign-born person becomes a citizen. The word comes from the Latin naturalis, meaning by birth: the law treats the new citizen as if they were native-born, with the same rights and duties.
Congress sets the requirements, and they have varied greatly across history. Today they typically include a period of lawful residence, good moral character, knowledge of English, and passing a civics test on American history and government, the kind of test many native-born citizens would struggle to pass.
The history is not always proud. For long stretches, naturalization was restricted by race; early law limited it to free white persons, and various groups were barred for generations. Who could become a citizen was, like who could vote, a contested line.
The process ends with an oath of allegiance, sworn at a naturalization ceremony. In that moment, often shared by people from dozens of countries at once, a person formally becomes a citizen, gaining the right to vote and the full membership of the republic.
