A Canadian law enacted in December 2025 has opened a new pathway to citizenship for descendants of Canadian-born residents who once lived in Buffalo. This legislation means that many individuals with historical ties to Canada through their ancestors in Buffalo may already hold Canadian citizenship.

In 1900, Buffalo was home to 17,242 people born in Canada, making up one in every 20 residents. Canadians formed the city's third largest immigrant group at that time, outnumbering those from Ireland and nearly doubling the combined total from England, Scotland, and Wales. Only Germany and Poland contributed more people to Buffalo.

The new law, Bill C-3, came into force on December 15, 2025. Previously, Canada limited citizenship by descent to the first generation born outside the country. Parliament removed this generational cutoff for anyone born before December 15, 2025, applying the change retroactively through generations.

Now, any individual with a single provable Canadian ancestor in their direct line of descent may already possess Canadian citizenship. These individuals need only apply to the Canadian federal government to formally prove their status.

The U.S. Census Office provided the 1900 figures for Canadian-born residents in Buffalo. Historically, English Canadians who moved to the United States were often overlooked by historians, according to Randy William Widdis, a historical geographer at the University of Regina. Widdis noted they were assumed to blend in quickly due to speaking the same language as their American neighbors.

U.S. census forms may also undercount Canadian ancestry. The term 'Canadian' does not appear as a sample answer for the ancestry question, though 'French Canadian' does. Census Bureau researchers have indicated that sample answers can boost reporting for listed groups and reduce it for unlisted ones. The Bureau also records only the first two ancestries provided, meaning many descendants of Canadians with English, Scottish, Irish, or German roots might identify with those older origins instead.

Claiming Canadian status carries no U.S. tax obligation, as both the United States and Canada permit dual citizenship. Applicants for proof of citizenship are not subject to a language test, residency requirement, or an oath.

Individuals can apply to the Canadian federal government to prove their status. This involves submitting a proof of citizenship application with supporting documentation that connects each generation in a direct line. The application traces the family one generation at a time, using records such as birth, marriage, baptismal, and death certificates.

A Canadian ancestor for a Buffalo family often originated from Ontario, across the Niagara River. Ontario divides its records between two offices, and civil registration began there in 1869. Older births may therefore rely on church records. As of September 2026, Immigration, Refugees and Citizenship Canada, or IRCC, estimates processing time for such an application at approximately 33 months.