This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
The Immigration and Nationality Act of 1965 ended the national origin quota system that had sharply restricted Asian immigration to the United States, removing the legal barrier that had kept large scale migration from South Asia from happening at all. The Hindu population in America began to grow substantially in the decades that followed, as South Asian immigrants arrived under the new law in numbers the old quota system had never permitted.
Before 1965, Hindu presence in America had been marginal, largely limited to occasional visiting teachers rather than any settled community; Swami Vivekananda's address at the 1893 World's Parliament of Religions stands as the best known example of that earlier, sporadic presence, a single address rather than the start of ongoing settlement. What followed the 1965 Act was different in kind, not merely in scale: an established diaspora with its own temples and institutions rather than a visiting teacher's occasional appearance.
What this changed for Hinduism's spread was the creation, within a single lifetime, of a Hindu population in the United States that reached an estimated size in the millions by the early twenty first century, built entirely on the migration a change in immigration law had made possible in 1965 and grown from a presence that had been, for over seventy years before it, no more than sporadic and occasional.