A bottoms-up, sourced estimate across 40 countries, counting only the U.S.-born descendants of America's immigrant waves.
Even excluding Mexico and Canada, about 11 million remain on the report's gross country-sum basis. The 25.281 million headline is de-duplicated, so country figures do not add to it.
U.S.-born, dual-compatible, and de-duplicated for people who qualify in more than one country.
Documented registrations in 2025 from the eight served countries that publish usable data. This is a floor because most countries publish nothing.
Under 4% of the eligible pool. The challenge is helping people complete the path, not finding enough eligible families.
Only 0.74% of the estimated eligible pool is represented in the documented annual count. The distance between the people who could reclaim a citizenship and those who do is the opportunity.
Millions of Americans identify with an ancestral country, but only some meet that country's current legal requirements. We applied the same discipline across 40 served countries, counting only U.S.-born descendants who can retain a U.S. passport.
Three countries account for about 83% of the eligible pool.
Top 15 of 40 served countries shown. The chart excludes appendix-only research countries and non-citizenship programs.
The largest eligible pool in the report. In 2025, 126,060 people obtained Mexican citizenship through this path, up 153% year over year. The remaining constraint is often the family record that proves the connection.
Read the full Mexico guide →Am I eligible? →Canada's Bill C-3 created the largest new opening in the report. About 56,000 U.S. applications were recorded by April 2026. For many families, the next question is whether their records connect them to a qualifying Canadian ancestor.
Read the full Canada guide →Am I eligible? →Ireland reaches many people with an Irish-born grandparent. About 19,000 U.S. applications were recorded in 2025, up 63% year over year, while millions of eligible grandchildren have not yet acted.
Read the full Ireland guide →Am I eligible? →Italy has an unusually visible awareness gap. Only 333,126 of roughly 16 million Americans with Italian ancestry are registered, about 2%. The path depends on the family line and the records that document it.
Read the full Italy guide →Am I eligible? →Our two-axis model weighs law permissiveness against emigration recency, anchored to U.S. Census/ACS ancestry, Pew/MPI foreign-born shares, and nationality law as of July 2026.
Download The Hidden Heirs, including full data tables, country breakdowns, the complete methodology, and what the estimate cannot tell you.
Figures are defensible estimates built from public data (U.S. Census/ACS ancestry, Pew/MPI foreign-born shares, and each country's nationality law as of July 2026), with explicit low/base/high ranges. They are research, not legal advice. Eligibility depends on your specific family documents and current law.Our bottoms-up estimate across 40 countries is ~25.3 million U.S.-born Americans. We count only those who could obtain a second citizenship and keep their U.S. passport. Ancestry counts are far larger, but ancestry is not eligibility.
Not necessarily. Each country has its own generational limits and rules. Ireland generally requires an Irish-born grandparent, while Italy tightened its rules to two generations in 2025. That is why the eligible number is a fraction of the ancestry number.
Mexico, Canada, and Ireland account for about 83% of the eligible pool. Italy is the fourth core opportunity because a large eligible population remains unregistered.
For the countries in our estimate, yes. We count only dual-compatible paths. India and Japan do not permit the counted dual-citizenship path, and Ethiopia's Yellow Card is residence rather than citizenship, so they are excluded from the eligible total.
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Heritage Passport Research · July 2026
Figures are defensible estimates built from public data (U.S. Census/ACS ancestry, Pew/MPI foreign-born shares, and each country's nationality law as of July 2026), with explicit low/base/high ranges. They are research, not legal advice. Eligibility depends on your specific family documents and current law.
