The Philadelphia naturalization records from 1789 to 1880 include detailed information on more than 113,000 immigrants representing nearly 100 countries. These early U.S. naturalization records are a vital source for anyone researching immigrant ancestors in Philadelphia. Filed in local and federal courts, these Pennsylvania naturalization documents help uncover names, countries of origin, and key citizenship dates—making them especially useful for exploring 18th and 19th-century immigration history.