Which amendment of the Constitution defines citizenship?

Within the United States Constitution, the 14th amendment defines citizenship and its requirements. This amendment was penned in response to the abolition of slavery, with the goal of securing the rights of former slaves.

The broad wording of the 14th amendment allows it to serve as an umbrella document that covers all the goals of its authors without being particularly specific as to whether it would eventually be expanded to include Native American populations as citizens. The indistinctness of the document and the continued indistinctness of Native American citizenship has resulted in the 14th amendment being generally associated with only the citizenship of ex-slaves and post-war reconstruction.