A photo of the Indian Citizenship Act of 1924. Until this act was passed Native Americans did not hold formal legal citizenship in the United States under federal law. Some acquired citizenship by marrying white men, others received citizenship through military service, by receipt of allotments, or through special treaties or special statutes. But many were still not citizens, and they were barred from the ordinary processes of naturalization open to foreigners. On June 2, 1924 Congress granted citizenship to all Native Americans born in the United States.