The Citizenship Clause is the first sentence of the Fourteenth Amendment to the United States Constitution, which was adopted on July 9, 1868, which states:
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.
This clause reversed a portion of the Dred Scott v. Sandford decision, which had declared that African Americans were not and could not become citizens of the United States or enjoy any of the privileges and immunities of citizenship.
The concepts of state and national citizenship were already mentioned in the original U.S. Constitution adopted in 1789, but the details were unclear. Prior to the Civil War, only some persons born or naturalized in the United States, and subject to the jurisdiction thereof, were citizens of the United States and of the state wherein they reside, according to the various applicable state and federal laws and court decisions.
The Civil Rights Act of 1866 granted U.S. citizenship to all persons born in the United States "not subject to any foreign power". The 39th Congress proposed the principle underlying the Citizenship Clause due to concerns expressed about the constitutionality of the Civil Rights Act during floor debates in Congress. The framers of the Fourteenth Amendment sought to entrench the principle in the Constitution in order to prevent its being struck down by the Supreme Court or repealed by a future Congress.