The United States and Canada still grow, and Mexico remains younger than either. North America shows how migration and an inherited age structure can keep a population rising after fertility falls below replacement.
The United States has remained below replacement since 2007. Final federal data recorded 3.63 million births in 2024. The general fertility rate fell slightly even as the number of births rose, because counts and rates use different denominators. The total fertility rate remained around 1.6 births per woman.
Canada has moved further. Its TFR reached 1.25 in 2024, entering the range the United Nations describes as ultra-low. Yet Canada had recently experienced rapid population growth because immigration added large numbers of people, many of them young adults. A national population can become larger while the family pattern beneath it moves further below replacement.
Mexico completes the continental reversal. Its 2023 demographic survey estimated TFR at 1.6, down from 2.07 in the comparable 2018 survey. Mexico retains a younger age structure, so births can remain numerous and population can grow after the period rate falls below replacement.
The old continental gradient has largely disappeared. The three countries now differ less in whether fertility is below replacement than in the age structures they inherited and the scale and direction of migration across their borders.
What immigration changes
Immigration changes national demography quickly because migrants are often young adults. The United Nations projects it to become the main driver of population growth in the United States, Canada, and dozens of other countries by the middle of the century.
The people moving are not entries shifted between ledgers. They leave one home and build another, changing both places. The narrower demographic point is that migration can alter a national population quickly without adding a person to the world total.
North America can therefore postpone visible contraction longer than places with older populations and less migration. The growth is real. It also keeps the fertility turn hidden beneath a rising national head count.
Citations
- National Center for Health Statistics, “Births and Natality”, final 2024 data.
- Statistics Canada, “Fertility and intentions: Socioeconomic factors”, January 26, 2026.
- Instituto Nacional de Estadística y Geografía, Encuesta Nacional de la Dinámica Demográfica 2023, 2024.
- United Nations, “Population”, based on the 2024 revision of World Population Prospects.