Why did immigration become a major source of Ontario’s population growth after the 1980s?

Immigration became a primary driver of population growth in Ontario after the 1980s primarily due to a significant decline in the province's birth rate.1

While natural increase—the difference between birth and death rates—had historically been the leading factor in population growth, the falling birth rate meant that natural increase could no longer sustain previous levels of growth. Consequently, immigration began to contribute far more to the province's population expansion than natural increase. This shift occurred alongside broader national trends where Canada increasingly relied on immigration to expand its workforce and domestic markets.12