Be aware that in 1776-1777, all men who supported the Revolution were automatically considered citizens. In 1778, the young nation established the Articles of Confederation which made all citizens of the states citizens of the United States.

The Naturalization Act was was passed by Congress in 1790. The act required residence in the state for one year, residence in the US for two years, and the taking of the loyalty oath in court. In 1799, the residence requirement changed to five years, and the immigrant was now required to "declare their intent" three years prior to taking their oath of allegiance. The declaration of intent and the taking of the oath could be taken in any county, state, or federal court. When a man was granted citizenship, his spouse and children of the male immigrant were automatically granted citizenship also.

The Bureau of Immigration and Naturalization was established in 1906. Starting in October 1906, the Bureau began keeping the naturalization records. If your ancestor was naturalized after that time, you should write to the Immigration and Naturalization Service for their naturalization records.