Why is NARA So Important to Genealogists? Census, military, passenger, and immigration records provide vital information such as birth, marriage, and death dates and places. They also may provide the names of parents, siblings, children, locations of birth, marriage, and death, and much more. If you have an ancestor who came to the United States after 1820, he or she may have applied for naturalization. Information can be found about his country of origin and his personal life.