As a country, we tend to focus on our European-based and Black History, often overlooking the earliest Native American inhabitants. The first inhabitants of what becomes the United States of America were the last to gain citizenship and the right to vote. They, too, experienced a period of enslavement in addition to loss of land, identity and culture and faced many generations of prejudicial treatment. Even with various programs and changes, as a people they are still struggling today.
On June 2, 1924:
The Snyder Act (Republican Homer P. Snyder of NY) put forth the "Indian Citizenship Act." which was made law June 2, 1924. 56 years after the 14th Amendment was ratified securing citizenship for black Americans-free or formerly enslaved.
The 14th Amendment to the Constitution was ratified on July 9, 1868, and granted citizenship to “all persons born or naturalized in the United States,” which included former slaves recently freed. The Amendment forbids states from denying any person "life, liberty or property, without due process of law" or to "deny to any person within its jurisdiction the equal protection of the laws.” By directly mentioning the role of the states, the 14th Amendment greatly expanded the protection of civil rights to all Americans and is cited in more litigation than any other amendment. EXCEPT for American Indians.
Up until 1924, the indigenous American Indians were not automatically citizens of the United States and were excluded from the rights and protections of the Constitution that the ordinary processes of naturalization opened to foreigners.
Some American Indians had acquired citizenship by marrying white men while others received citizenship through military service, by receipt of allotments, or through special treaties or special statutes. But many were still not citizens.
Native Americans had demonstrated their ability to assimilate into the general military society in WW I. There were no segregated Indian units as there were for black Americans. Some members of the white society declared that the Indians had successfully passed the assimilation test during wartime, and thus they deserved the rewards of citizenship.
Congress took what some saw as the final step on June 2, 1924 and granted citizenship to all Native Americans born in the United States.
BE IT ENACTED by the Senate and house of Representatives of the United States of America in Congress assembled, That all non citizen Indians born within the territorial limits of the United States be, and they are hereby, declared to be citizens of the United States: Provided That the granting of such citizenship shall not in any manner impair or otherwise affect the right of any Indian to tribal or other property. (Approved June 2, 1924)