To claim India citizenship by descent from United States, you need: (1) an Indian ancestor in your direct line, (2) proof they were an Indian citizen at the time of the next child's birth, (3) the chain of vital records linking you to that ancestor, and (4) apostilles and certified translations of all United Statesn documents.
Emigration era
1965-present (post-1965 US immigration reform, UK Commonwealth migration)
Volume
Significant Indian emigration to United States
Key ports
Departure ports: Bombay (Mumbai), Madras (Chennai), Calcutta (Kolkata). Arrival ports: Ellis Island (New York), Castle Garden (New York, pre-1892), Boston, Philadelphia, San Francisco.
Consulate
Indian consulate/embassy in United States
Push factors (why they left India)
Pull factors (why they chose United States)
Naturalization & document retrieval
United States naturalization records are held by USCIS (US Citizenship and Immigration Services) and NARA (National Archives). For CBD cases, the critical question is whether your Indian ancestor naturalized in United States BEFORE or AFTER the next child's birth. If BEFORE, the citizenship chain is broken (in most countries). If AFTER (or never), the chain is intact.
Start with the Indian ancestor's birth certificate from their place of birth in India. This is the foundational document.
Search USCIS (US Citizenship and Immigration Services) and NARA (National Archives) for the ancestor's naturalization record. If none found, request a formal "no record" letter.
Check Ellis Island, Castle Garden, and NARA ship manifests for the ancestor's arrival record, which shows date, port, and citizenship status at arrival.
Review US Federal Census (1900-1950, available via NARA and Ancestry) to track the ancestor's residence and citizenship status over time.
Obtain certified long-form birth certificates for each person in the chain between you and your Indian ancestor.
Related resources