Margaret Sanger, "The Arithmetics of the Problem of Population," 07 Nov 1931.

Source: "Margaret Sanger Papers, Sophia Smith Collection Margaret Sanger Microfilm, Smith College Collections S71:236."

Sanger drafted these notes in Houston, likely for her Nov. 7 appearance there. For another version of this speech, see "The Problem of Population" Nov. 1932.


The arithmetics of the problem of Population has too long been ignored. The almost universal custom of assuming in all discussions of population problems that the birth rate by itself is the indication of the increase or decrease of the population one reads editorials & articles & hears lectures make this error over & over again that the decline of the birth rate means a decrease in population.

It must come from our [one word illegible] school day dislike of arithmetics. You would not make the same mistake if you ↑ [in?] ↓ were calculating your income from investments found that a decline in the rate of interest had been accompanied by more than an equivalent in the increase in the amount of capital. Every one depending on income knows that it depends not only on the rate of the dividend, but also upon the amount of capital on which the dividend is paid.

So the same arithmetics & consideration must be applied to population statistics. For the growth of population depends not only on births, but on the excess of births over deaths. And the important point to remember is that a birth rate by itself can not possibly give any indication of the rapidity with which a population is growing unless we know the volume to which the rate is applied.

An excellent illustration of this fact may be given from the figures representing the growth in the population of N.Y.City During the first 20 years of the 19 Century N.Y.C. nearly doubled its population. The rate of ↑actual increase↓ increase being 92% or 73,000. In the first 20 years of the present century with a lowered rate of 63% the actual increase was 2,183,000.

To deplore the falling birth rate without knowing the volume to which the rate is applied is like a man boasting of his riches because he gets 50% interest--on what his whole capital being $100. While another man complains of his poverty because his he can only get a dividend of 5% on a capital of 50,000 or a million.

The meat of the above in a nutshell is: Where the population is increasing the rate of increase tends to decline. In USA from ↑in↓ 1800 the rate of increase was 36%. In 1920 it fell to 15% while the actual numbers increased from 5,308 ↑2,400,000↓ to 105,711 ↑13,740,000↓ .

There is no need to argue that our population problem is complicated by the immigration from other countries. We accept that point, but the case in point & the law applies equally to other countries like England & France where the growth of population is due entirely to her natural increase.

No country can continue to stand a doubling of its population every 50 years as ours has done in the past. Take the case of a baby's growth. When born it weighs 7 lbs normally it doubles its weight in the first 5 or 6 months But should it continue to double its weight every succeeding 5 months By the time it was five years old it would weigh nearly 13 tons. Ten months later it would weigh nearly 50 tons! The same law of growth applied to the child governs the growth of every [rest of document missing]


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