In 2018 there were 3.85 million births and 2.81 million deaths.

My understanding is that the U.S. birth rate is near or below replacement rate, but I don't understand why. If more people are being born than are dying, won't the population continue to grow?


When you hear that "the U.S. birth rate is near or below replacement rate", what is probably meant is that the total fertility rate (TFR) is below 2.1 (replacement rate).

It is possible that the TFR is below 2.1, while births exceed deaths. One way this can happen is if there's a rising share of women entering reproductive age.

This phenomenon is sometimes called population momentum (more details: 1, 2, 3).

This is actually a fairly common phenomenon: Many countries have had TFR below 2.1 for many years but their populations have continued to grow. For example, China has had TFR below 2.1 since 1992 but births have continued to exceed deaths every year.

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  • $\begingroup$ I see; so what it boils down to then is that the generation that is currently in its childbearing years is having enough children to replace the older, smaller generation, but is not actually having enough children to replace itself, a much larger generation. $\endgroup$ – David Kennell Aug 11 at 21:09

This answers your question. Apparently the replacement rate for the population of the US is when the average birth rate of specificly aged women is at 2.1 babies per woman. Annual deaths and births are probably not a bad indication of population growth, but when it comes to this specific measure (the replacement rate), they are irrelevant.

I just have to say, I personally wouldn't post such a question on an Economics SE. Perhaps it's best that you move it to the Statistics SE.

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  • $\begingroup$ Could you copy the gist of your link into your answer. Link only answers are discouraged here, as links break overtime. $\endgroup$ – Giskard Aug 10 at 19:43
  • $\begingroup$ Weren't you about to vote to close this question down? $\endgroup$ – the_rainbox Aug 10 at 20:09
  • $\begingroup$ No, but I understand your concern and I am also not sure if it is on topic. Still, please edit your answer so I can upvote it. $\endgroup$ – Giskard Aug 10 at 20:28
  • $\begingroup$ Oops, I expected that such a long article was about how population demographics/size difference in age cohorts would explain the discrepancy between current birth/death ratios and the replacement rate. Currently the discrepancy is not explained. (Downvote not by me though.) $\endgroup$ – Giskard Aug 11 at 6:48
  • $\begingroup$ There is no explanation for this discrepancy because the two phenomena are unrelated, which is easily inferred from reading the document. $\endgroup$ – the_rainbox Aug 11 at 7:40

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